ELI5-ification underway\!
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README.rst
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README.rst
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Synopsis
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Synopsis
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--------
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--------
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**Polyloader** is a python module that enables the discovery and loading
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**Polyloader** is a python module that extends the Python `import`
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of heterogenous source code packages. This discovery and loading is
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statement to enable the discovery and loading of heterogenous source
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critical to the functioning of other programming languages that use the
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Python AST and Python interpreter, languages such as Hy, Doge, and
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Mochi.
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Problem Statement
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-----------------
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The Python module loader system is hard-coded to prevent the discovery
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of heterogenous source code packages. From Python 2.6 through the
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current (as of this writing) Python 3.5, the import mechanism allows for
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the creation of file finders and importers that would transform Python's
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import syntax into a *path,* assert whether or not that path could be
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made to correspond to a *syntax object*, and then attempt to *load* that
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syntax object as a Python module. Python *packages*, however, are
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assumed to be uniformly made up of Python syntax objects, be they
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**.py** source files, **.pyc/.pyo** bytecode, or **.so/.dll** files with
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an exposed Python-to-C API. In Python 2 these suffixes are hard-coded
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into the source in the **imp** builtin module; in Python 3 these
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suffixes are constants defined in a private section of **importlib**; in
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either case, they are unavailable for modification. This lack of access
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to the extensions list prevents the *discovery* of heterogenous source
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code packages.
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code packages.
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The discovery mechanism is outlined in Python's **pkgutil** module;
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Say What?
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features such as **pkgutil.iter_modules** do not work with heterogenous
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---------
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source code, which in turn means that one cannot write, for one
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important example, Django management commands in an alternative syntax.
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**polyloader** is a Python module that intercepts calls to the default
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The ``import`` statement is how the Python interpreter finds a module
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finder, loader, and package module iterator, and if the path resolves to
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written in Python and loads it, turning it into variables, executable
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an alternative syntax, provide the appropriate finder, loader and
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functions, constructable classes, and other Python objects, and then
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iterator. **polyloader** is different from traditional importlib shims
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exposes those objects to the currently running program.
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in that it directly affects the default source file loader, and thus
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allows for the discovery and importation of suffixes not listed in
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Python's defaults.
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To use:
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The ``import`` statement has long been extensible so that things other
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-------
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than Python code could be imported, but this feature has always had two
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limitations:
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Import polyloader in your python script's launcher or library, as well
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1. It's annoyingly hard to write an importer. (Believe me. Polyloader
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as the syntax compiler(s) you plan to use. For example, if you have
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*is* one!)
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`Mochi <https://github.com/i2y/mochi>`__ and
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2. For filesystem-based modules (which is 99% of them) Python's importer
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`Hy <http://docs.hylang.org/en/latest/>`__ installed, and you wanted to
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only understands one loader type per directory. It's not possible to
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write a Django app, edit manage.py and add the following lines at the
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store code or data written in something other than Python in the same
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top:
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directory with Python module code and load it via ``import``.
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::
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The former requires a certain degree of abstraction and thought. For
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the latter, most people ignore the problem and load module configuration
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files written in JSON or YAML or whatever directly. This is fine,
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except when you want to write in one of Python's extended languages like
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Hy or Coconut in a framework like Django, Flask or Glitch.
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from mochi.main import compile_file as mochi_compile
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**Polyloader** eliminates these limitations.
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from hy.importer import ast_compile as hy_compile
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from polyloader import polyimport
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polyimport(mochi_compile, ['.mochi'])
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polyimport(hy_compile, ['.hy'])}
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Now your views can be written in Hy and your models in Mochi, and
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What's the real problem?
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everything will just work.
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------------------------
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Dependencies
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The real problem is that Python's traditional extensions, ``.py``,
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------------
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``.pyc/.pyo``, and ``.so/.dll`` files, are hard-coded in Python. In
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Python 2, they're in the ``imp`` builtin; In Python 3, they're defined
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in a private section of `importlib`. Either way, they're not accessible
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for modification and extension.
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This problem is made harder by the ``pkglib`` module, which is part of
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Python's standard library. This module uses ``inspect.getmoduleinfo``,
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which again only recognizes the usual extensions. Which means you can't
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list multilingual modules either; this hampers the development of Django
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management commands in a syntax other than Python.
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What the solution?
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------------------
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At its heart, the Python import system runs two different internal
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mechanisms to figure out what the *import string* (the dotted terms
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after the word "import") "means." Each mechanism has one or more
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*finders*, and the first finder to report "I have a *loader* that knows
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what that import string means" wins.
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The very last finder is for the filesystem. The solution is to get in
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front of that finder with one that can handle all the other syntax
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loaders *and* knows how to fall back on the last one for those files the
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last one handles.
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That's what ``polyloader`` does.
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polymorph is self-contained. It has no dependencies other than Python
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itself and your choice of language.
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Details on Import and Polyloader
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================================
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Welcome to the Python Import ELI5!
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**********************************
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What is `import`?
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-----------------
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``import`` is a Python statement that finds a *module* that is accessible
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by the currently running process, loads it, and makes its contents
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available to the scope in which the statement was made. A statement
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like
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``import django.db.models``
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is looking for a module named ``django.db.models``. If the statement is
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successful, ``django.db.models`` will be a variable name in the scope,
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it will be a Python *object* (of ``class Module``, but that's not
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important), and it will have functions, class constructors, variables
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and constants. These Python objects will be accessible through the dot
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operator.
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An alternative way of writing import statements is
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``from django.utils import encoding``
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And then the variable will just be ``encoding``. The ``encoding``
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module has a function for handling unicode-to-web translation.
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Accessing it through the dot operator, it looks like this:
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``ready_str = encoding.smart_str(unready_str)``
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We call the parts of the import statement that describe the module the
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*import string*.
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``sys.path_hooks``: How does Python know where to look?
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-------------------------------------------------------
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That's what's funny. Python has two independent ways of making sense of
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of the import string. The old system is based on the assumption that
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everything is a filesystem, with folders and filenames. This is called
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the ``sys.path_hooks`` system.
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In the old system, the parts of the import string would be split up, and
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then a collection of directories would be scanned to see if the first
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name in the import string could be matched with a subdirectory. If it
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could, that directory would be scanned until the last name on the import
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string. If that name was a *filename*, it would be loaded as a module.
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If that name was a *directory* and that directory had a file named
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``__init__.py``, then that file would be loaded as the module.
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The ``sys.path_hooks`` array has a list of different methods for trying to
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scan a filesystem for the parts of the import string. A ``path_hook`` is
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a function that takes a path to a directory; if it can handle the
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contents of the directory, it returns a **Finder**, an object whose job
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is to figure out how to load the module; if it can't, it returns an
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ImportError exception. The object that loads the module is called,
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naturally, a **Loader**.
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* To read more about **Finders**, see :ref:`eli5-finders`
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* To read more about **Loaders**, see :ref:`eli5-loaders`
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* To read more about **Path Hooks**, see :ref:`eli5-pathhooks`
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``sys.path``: What directories are searched?
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--------------------------------------------
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The list of directories is stored in an array, ``sys.path``. This path is
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initialized by Python when it starts up, but programs can modify it at
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run-time to point to extra directories if they want.
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``sys.meta_path``: What is the new system?
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------------------------------------------
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The new system is called ``sys.meta_path``, and it's an array of
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**Finders**, objects that have one method, ``find_module(fullname)``.
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It's an anything-goes API that gives developers the freedom to import
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modules from anywhere: databases, archives, remote web resources, even
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code written on-the-fly internally. The new system can apply any
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meaning at all to the import string.
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In Python, the import string is offered to each object in
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``sys.meta_path`` before being offered to each ``sys.path_hook``. The
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filesystem is typically the last finder tried.
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To read more about **Meta Paths**, see :ref:`eli5-metapaths`
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Is it different between Python 2 and Python 3?
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---------------------------------------------
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Python 3 moves almost everything about this process into python's
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library, leaving only a bare minimum of functionality inside the Python
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executable to load this library and run it. When the Python developers
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did that, they added a lot of functionality to make it easier to write
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new import modules. The old way still works, but there are now *Module
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Specifications*, which are metadata about a module, and the old
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``path_hooks`` system is now just a ``meta_path`` handler added to the
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new system as the last resort.
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To read more about **Module Specifications**, see :ref:`eli5-specs`
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Does the old system still matter?
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---------------------------------
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Yes, for one reason: *iteration*. Iteration is the ability to take a
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path where you believe Python modules can be found, and list through
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them. This facility is useful for large frameworks where a user wants
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to add new commands, or new objects, or new operations; Django uses this
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facility a lot! The ``pkgutil`` library depends upon Finders being able
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to iterate their contents.
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ELI5: Explain Like I'm Five!
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============================
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.. _eli5-finders:
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Finders
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=======
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TODO
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.. _eli5-loaders:
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Loaders
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=======
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TODO
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.. _eli5-pathhooks:
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Path Hooks
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==========
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TODO
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.. _eli5-metapaths:
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Meta Paths
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==========
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TODO
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.. _eli5-specs:
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Module Specifications
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=====================
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TODO
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You can adapt this file completely to your liking, but it should at least
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You can adapt this file completely to your liking, but it should at least
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contain the root `toctree` directive.
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contain the root `toctree` directive.
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Welcome to py-polymorphic-loader's documentation!
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Welcome to polyloader
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======================================
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=====================
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Contents:
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Contents:
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@ -14,6 +14,7 @@ Contents:
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readme
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readme
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installation
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installation
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usage
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usage
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details
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contributing
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contributing
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authors
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authors
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history
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history
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@ -8,11 +8,11 @@ Installation
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Stable release
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Stable release
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--------------
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--------------
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To install py-polymorphic-loader, run this command in your terminal:
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To install polyloader, run this command in your terminal:
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.. code-block:: console
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.. code-block:: console
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$ pip install py-polymorphic-loader
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$ pip install polyloader
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If you don't have `pip`_ installed, this `Python installation guide`_ can guide
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If you don't have `pip`_ installed, this `Python installation guide`_ can guide
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you through the process.
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you through the process.
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@ -24,19 +24,19 @@ you through the process.
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From sources
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From sources
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------------
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------------
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The sources for py-polymorphic-loader can be downloaded from the `Github repo`_.
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The sources for polyloader can be downloaded from the `Github repo`_.
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You can either clone the public repository:
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You can either clone the public repository:
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.. code-block:: console
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.. code-block:: console
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$ git clone git://github.com/elfsternberg/py-polymorphic-loader
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$ git clone git://github.com/elfsternberg/polyloader
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Or download the `tarball`_:
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Or download the `tarball`_:
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.. code-block:: console
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.. code-block:: console
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$ curl -OL https://github.com/elfsternberg/py-polymorphic-loader/tarball/master
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$ curl -OL https://github.com/elfsternberg/polyloader/tarball/master
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Once you have a copy of the source, you can install it with:
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Once you have a copy of the source, you can install it with:
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@ -45,5 +45,5 @@ Once you have a copy of the source, you can install it with:
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$ python setup.py install
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$ python setup.py install
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.. _Github repo: https://github.com/elfsternberg/py-polymorphic-loader
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.. _Github repo: https://github.com/elfsternberg/polyloader
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.. _tarball: https://github.com/elfsternberg/py-polymorphic-loader/tarball/master
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.. _tarball: https://github.com/elfsternberg/polyloader/tarball/master
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@ -1 +1 @@
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.. include:: ../README.rst
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.. include:: ../../README.rst
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@ -2,6 +2,21 @@
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Usage
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Usage
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=====
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=====
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To use py-polymorphic-loader in a project::
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Import polyloader in your python script's launcher or library, as well
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as the syntax compiler(s) you plan to use. For example, if you have
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`Mochi <https://github.com/i2y/mochi>`__ and `Hy
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<http://docs.hylang.org/en/latest/>`__ installed, and you wanted to
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write a Django app, edit manage.py and add the following lines at the
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top:
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::
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from mochi.main import compile_file as mochi_compile
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from hy.importer import ast_compile as hy_compile
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import polyloader
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polyloader.install(mochi_compile, ['.mochi'])
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polyloader.install(hy_compile, ['.hy'])}
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Now your views can be written in Hy and your models in Mochi, and
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everything will just work.
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import py-polymorphic-loader
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<script type="text/javascript" src="doctools.js"></script>
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<script type="text/javascript" src="doctools.js"></script>
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<link rel="top" title="polyloader 0.1.0 documentation" href="index.html" />
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<link rel="top" title="polyloader 0.1.0 documentation" href="index.html" />
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<link rel="next" title="<no title>" href="authors.html" />
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<link rel="next" title="<no title>" href="authors.html" />
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<link rel="prev" title="Usage" href="usage.html" />
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<link rel="prev" title="Details on Import and Polyloader" href="details.html" />
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</head>
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</head>
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<body>
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<body>
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||||||
<div class="related">
|
<div class="related">
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|
@ -41,7 +41,7 @@
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<a href="authors.html" title="<no title>"
|
<a href="authors.html" title="<no title>"
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||||||
accesskey="N">next</a> |</li>
|
accesskey="N">next</a> |</li>
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<li class="right" >
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<li class="right" >
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<a href="usage.html" title="Usage"
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<a href="details.html" title="Details on Import and Polyloader"
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accesskey="P">previous</a> |</li>
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accesskey="P">previous</a> |</li>
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<li><a href="index.html">polyloader 0.1.0 documentation</a> »</li>
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<li><a href="index.html">polyloader 0.1.0 documentation</a> »</li>
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</ul>
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</ul>
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<div class="section" id="details-on-import-and-polyloader">
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<h1>Details on Import and Polyloader<a class="headerlink" href="#details-on-import-and-polyloader" title="Permalink to this headline">¶</a></h1>
|
||||||
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<div class="section" id="welcome-to-the-python-import-eli5">
|
||||||
|
<h2>Welcome to the Python Import ELI5!<a class="headerlink" href="#welcome-to-the-python-import-eli5" title="Permalink to this headline">¶</a></h2>
|
||||||
|
<div class="section" id="what-is-import">
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||||||
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<h3>What is <cite>import</cite>?<a class="headerlink" href="#what-is-import" title="Permalink to this headline">¶</a></h3>
|
||||||
|
<p><tt class="docutils literal"><span class="pre">import</span></tt> is a Python statement that finds a <em>module</em> that is accessible
|
||||||
|
by the currently running process, loads it, and makes its contents
|
||||||
|
available to the scope in which the statement was made. A statement
|
||||||
|
like</p>
|
||||||
|
<p><tt class="docutils literal"><span class="pre">import</span> <span class="pre">django.db.models</span></tt></p>
|
||||||
|
<p>is looking for a module named <tt class="docutils literal"><span class="pre">django.db.models</span></tt>. If the statement is
|
||||||
|
successful, <tt class="docutils literal"><span class="pre">django.db.models</span></tt> will be a variable name in the scope,
|
||||||
|
it will be a Python <em>object</em> (of <tt class="docutils literal"><span class="pre">class</span> <span class="pre">Module</span></tt>, but that’s not
|
||||||
|
important), and it will have functions, class constructors, variables
|
||||||
|
and constants. These Python objects will be accessible through the dot
|
||||||
|
operator.</p>
|
||||||
|
<p>An alternative way of writing import statements is</p>
|
||||||
|
<p><tt class="docutils literal"><span class="pre">from</span> <span class="pre">django.utils</span> <span class="pre">import</span> <span class="pre">encoding</span></tt></p>
|
||||||
|
<p>And then the variable will just be <tt class="docutils literal"><span class="pre">encoding</span></tt>. The <tt class="docutils literal"><span class="pre">encoding</span></tt>
|
||||||
|
module has a function for handling unicode-to-web translation.
|
||||||
|
Accessing it through the dot operator, it looks like this:</p>
|
||||||
|
<p><tt class="docutils literal"><span class="pre">ready_str</span> <span class="pre">=</span> <span class="pre">encoding.smart_str(unready_str)</span></tt></p>
|
||||||
|
<p>We call the parts of the import statement that describe the module the
|
||||||
|
<em>import string</em>.</p>
|
||||||
|
</div>
|
||||||
|
<div class="section" id="sys-path-hooks-how-does-python-know-where-to-look">
|
||||||
|
<h3><tt class="docutils literal"><span class="pre">sys.path_hooks</span></tt>: How does Python know where to look?<a class="headerlink" href="#sys-path-hooks-how-does-python-know-where-to-look" title="Permalink to this headline">¶</a></h3>
|
||||||
|
<p>That’s what’s funny. Python has two independent ways of making sense of
|
||||||
|
of the import string. The old system is based on the assumption that
|
||||||
|
everything is a filesystem, with folders and filenames. This is called
|
||||||
|
the <tt class="docutils literal"><span class="pre">sys.path_hooks</span></tt> system.</p>
|
||||||
|
<p>In the old system, the parts of the import string would be split up, and
|
||||||
|
then a collection of directories would be scanned to see if the first
|
||||||
|
name in the import string could be matched with a subdirectory. If it
|
||||||
|
could, that directory would be scanned until the last name on the import
|
||||||
|
string. If that name was a <em>filename</em>, it would be loaded as a module.
|
||||||
|
If that name was a <em>directory</em> and that directory had a file named
|
||||||
|
<tt class="docutils literal"><span class="pre">__init__.py</span></tt>, then that file would be loaded as the module.</p>
|
||||||
|
<p>The <tt class="docutils literal"><span class="pre">sys.path_hooks</span></tt> array has a list of different methods for trying to
|
||||||
|
scan a filesystem for the parts of the import string. A <tt class="docutils literal"><span class="pre">path_hook</span></tt> is
|
||||||
|
a function that takes a path to a directory; if it can handle the
|
||||||
|
contents of the directory, it returns a <strong>Finder</strong>, an object whose job
|
||||||
|
is to figure out how to load the module; if it can’t, it returns an
|
||||||
|
ImportError exception. The object that loads the module is called,
|
||||||
|
naturally, a <strong>Loader</strong>.</p>
|
||||||
|
<ul class="simple">
|
||||||
|
<li>To read more about <strong>Finders</strong>, see <a class="reference internal" href="eli5.html#eli5-finders"><em>Finders</em></a></li>
|
||||||
|
<li>To read more about <strong>Loaders</strong>, see <a class="reference internal" href="eli5.html#eli5-loaders"><em>Loaders</em></a></li>
|
||||||
|
<li>To read more about <strong>Path Hooks</strong>, see <a class="reference internal" href="eli5.html#eli5-pathhooks"><em>Path Hooks</em></a></li>
|
||||||
|
</ul>
|
||||||
|
</div>
|
||||||
|
<div class="section" id="sys-path-what-directories-are-searched">
|
||||||
|
<h3><tt class="docutils literal"><span class="pre">sys.path</span></tt>: What directories are searched?<a class="headerlink" href="#sys-path-what-directories-are-searched" title="Permalink to this headline">¶</a></h3>
|
||||||
|
<p>The list of directories is stored in an array, <tt class="docutils literal"><span class="pre">sys.path</span></tt>. This path is
|
||||||
|
initialized by Python when it starts up, but programs can modify it at
|
||||||
|
run-time to point to extra directories if they want.</p>
|
||||||
|
</div>
|
||||||
|
<div class="section" id="sys-meta-path-what-is-the-new-system">
|
||||||
|
<h3><tt class="docutils literal"><span class="pre">sys.meta_path</span></tt>: What is the new system?<a class="headerlink" href="#sys-meta-path-what-is-the-new-system" title="Permalink to this headline">¶</a></h3>
|
||||||
|
<p>The new system is called <tt class="docutils literal"><span class="pre">sys.meta_path</span></tt>, and it’s an array of
|
||||||
|
<strong>Finders</strong>, objects that have one method, <tt class="docutils literal"><span class="pre">find_module(fullname)</span></tt>.
|
||||||
|
It’s an anything-goes API that gives developers the freedom to import
|
||||||
|
modules from anywhere: databases, archives, remote web resources, even
|
||||||
|
code written on-the-fly internally. The new system can apply any
|
||||||
|
meaning at all to the import string.</p>
|
||||||
|
<p>In Python, the import string is offered to each object in
|
||||||
|
<tt class="docutils literal"><span class="pre">sys.meta_path</span></tt> before being offered to each <tt class="docutils literal"><span class="pre">sys.path_hook</span></tt>. The
|
||||||
|
filesystem is typically the last finder tried.</p>
|
||||||
|
<p>To read more about <strong>Meta Paths</strong>, see <a class="reference internal" href="eli5.html#eli5-metapaths"><em>Meta Paths</em></a></p>
|
||||||
|
</div>
|
||||||
|
<div class="section" id="is-it-different-between-python-2-and-python-3">
|
||||||
|
<h3>Is it different between Python 2 and Python 3?<a class="headerlink" href="#is-it-different-between-python-2-and-python-3" title="Permalink to this headline">¶</a></h3>
|
||||||
|
<p>Python 3 moves almost everything about this process into python’s
|
||||||
|
library, leaving only a bare minimum of functionality inside the Python
|
||||||
|
executable to load this library and run it. When the Python developers
|
||||||
|
did that, they added a lot of functionality to make it easier to write
|
||||||
|
new import modules. The old way still works, but there are now <em>Module
|
||||||
|
Specifications</em>, which are metadata about a module, and the old
|
||||||
|
<tt class="docutils literal"><span class="pre">path_hooks</span></tt> system is now just a <tt class="docutils literal"><span class="pre">meta_path</span></tt> handler added to the
|
||||||
|
new system as the last resort.</p>
|
||||||
|
<p>To read more about <strong>Module Specifications</strong>, see <a class="reference internal" href="eli5.html#eli5-specs"><em>Module Specifications</em></a></p>
|
||||||
|
</div>
|
||||||
|
<div class="section" id="does-the-old-system-still-matter">
|
||||||
|
<h3>Does the old system still matter?<a class="headerlink" href="#does-the-old-system-still-matter" title="Permalink to this headline">¶</a></h3>
|
||||||
|
<p>Yes, for one reason: <em>iteration</em>. Iteration is the ability to take a
|
||||||
|
path where you believe Python modules can be found, and list through
|
||||||
|
them. This facility is useful for large frameworks where a user wants
|
||||||
|
to add new commands, or new objects, or new operations; Django uses this
|
||||||
|
facility a lot! The <tt class="docutils literal"><span class="pre">pkgutil</span></tt> library depends upon Finders being able
|
||||||
|
to iterate their contents.</p>
|
||||||
|
</div>
|
||||||
|
</div>
|
||||||
|
</div>
|
||||||
|
|
||||||
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||||||
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<div class="sphinxsidebar">
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||||||
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<h3><a href="index.html">Table Of Contents</a></h3>
|
||||||
|
<ul>
|
||||||
|
<li><a class="reference internal" href="#">Details on Import and Polyloader</a><ul>
|
||||||
|
<li><a class="reference internal" href="#welcome-to-the-python-import-eli5">Welcome to the Python Import ELI5!</a><ul>
|
||||||
|
<li><a class="reference internal" href="#what-is-import">What is <cite>import</cite>?</a></li>
|
||||||
|
<li><a class="reference internal" href="#sys-path-hooks-how-does-python-know-where-to-look"><tt class="docutils literal"><span class="pre">sys.path_hooks</span></tt>: How does Python know where to look?</a></li>
|
||||||
|
<li><a class="reference internal" href="#sys-path-what-directories-are-searched"><tt class="docutils literal"><span class="pre">sys.path</span></tt>: What directories are searched?</a></li>
|
||||||
|
<li><a class="reference internal" href="#sys-meta-path-what-is-the-new-system"><tt class="docutils literal"><span class="pre">sys.meta_path</span></tt>: What is the new system?</a></li>
|
||||||
|
<li><a class="reference internal" href="#is-it-different-between-python-2-and-python-3">Is it different between Python 2 and Python 3?</a></li>
|
||||||
|
<li><a class="reference internal" href="#does-the-old-system-still-matter">Does the old system still matter?</a></li>
|
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</ul>
|
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|
</li>
|
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|
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|
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|
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|
accesskey="I">index</a></li>
|
||||||
|
<li class="right" >
|
||||||
|
<a href="py-modindex.html" title="Python Module Index"
|
||||||
|
>modules</a> |</li>
|
||||||
|
<li><a href="index.html">polyloader 0.1.0 documentation</a> »</li>
|
||||||
|
</ul>
|
||||||
|
</div>
|
||||||
|
|
||||||
|
<div class="document">
|
||||||
|
<div class="documentwrapper">
|
||||||
|
<div class="bodywrapper">
|
||||||
|
<div class="body">
|
||||||
|
|
||||||
|
<div class="section" id="eli5-explain-like-i-m-five">
|
||||||
|
<h1>ELI5: Explain Like I’m Five!<a class="headerlink" href="#eli5-explain-like-i-m-five" title="Permalink to this headline">¶</a></h1>
|
||||||
|
</div>
|
||||||
|
<div class="section" id="finders">
|
||||||
|
<span id="eli5-finders"></span><h1>Finders<a class="headerlink" href="#finders" title="Permalink to this headline">¶</a></h1>
|
||||||
|
<p>TODO</p>
|
||||||
|
</div>
|
||||||
|
<div class="section" id="loaders">
|
||||||
|
<span id="eli5-loaders"></span><h1>Loaders<a class="headerlink" href="#loaders" title="Permalink to this headline">¶</a></h1>
|
||||||
|
<p>TODO</p>
|
||||||
|
</div>
|
||||||
|
<div class="section" id="path-hooks">
|
||||||
|
<span id="eli5-pathhooks"></span><h1>Path Hooks<a class="headerlink" href="#path-hooks" title="Permalink to this headline">¶</a></h1>
|
||||||
|
<p>TODO</p>
|
||||||
|
</div>
|
||||||
|
<div class="section" id="meta-paths">
|
||||||
|
<span id="eli5-metapaths"></span><h1>Meta Paths<a class="headerlink" href="#meta-paths" title="Permalink to this headline">¶</a></h1>
|
||||||
|
<p>TODO</p>
|
||||||
|
</div>
|
||||||
|
<div class="section" id="module-specifications">
|
||||||
|
<span id="eli5-specs"></span><h1>Module Specifications<a class="headerlink" href="#module-specifications" title="Permalink to this headline">¶</a></h1>
|
||||||
|
<p>TODO</p>
|
||||||
|
</div>
|
||||||
|
|
||||||
|
|
||||||
|
</div>
|
||||||
|
</div>
|
||||||
|
</div>
|
||||||
|
<div class="sphinxsidebar">
|
||||||
|
<div class="sphinxsidebarwrapper">
|
||||||
|
<h3><a href="index.html">Table Of Contents</a></h3>
|
||||||
|
<ul>
|
||||||
|
<li><a class="reference internal" href="#">ELI5: Explain Like I’m Five!</a></li>
|
||||||
|
<li><a class="reference internal" href="#finders">Finders</a></li>
|
||||||
|
<li><a class="reference internal" href="#loaders">Loaders</a></li>
|
||||||
|
<li><a class="reference internal" href="#path-hooks">Path Hooks</a></li>
|
||||||
|
<li><a class="reference internal" href="#meta-paths">Meta Paths</a></li>
|
||||||
|
<li><a class="reference internal" href="#module-specifications">Module Specifications</a></li>
|
||||||
|
</ul>
|
||||||
|
|
||||||
|
<h3>This Page</h3>
|
||||||
|
<ul class="this-page-menu">
|
||||||
|
<li><a href="_sources/eli5.txt"
|
||||||
|
rel="nofollow">Show Source</a></li>
|
||||||
|
</ul>
|
||||||
|
<div id="searchbox" style="display: none">
|
||||||
|
<h3>Quick search</h3>
|
||||||
|
<form class="search" action="search.html" method="get">
|
||||||
|
<input type="text" name="q" />
|
||||||
|
<input type="submit" value="Go" />
|
||||||
|
<input type="hidden" name="check_keywords" value="yes" />
|
||||||
|
<input type="hidden" name="area" value="default" />
|
||||||
|
</form>
|
||||||
|
<p class="searchtip" style="font-size: 90%">
|
||||||
|
Enter search terms or a module, class or function name.
|
||||||
|
</p>
|
||||||
|
</div>
|
||||||
|
<script type="text/javascript">$('#searchbox').show(0);</script>
|
||||||
|
</div>
|
||||||
|
</div>
|
||||||
|
<div class="clearer"></div>
|
||||||
|
</div>
|
||||||
|
<div class="related">
|
||||||
|
<h3>Navigation</h3>
|
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|
<ul>
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||||||
|
<li class="right" style="margin-right: 10px">
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||||||
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<a href="genindex.html" title="General Index"
|
||||||
|
>index</a></li>
|
||||||
|
<li class="right" >
|
||||||
|
<a href="py-modindex.html" title="Python Module Index"
|
||||||
|
>modules</a> |</li>
|
||||||
|
<li><a href="index.html">polyloader 0.1.0 documentation</a> »</li>
|
||||||
|
</ul>
|
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|
</div>
|
||||||
|
<div class="footer">
|
||||||
|
© Copyright 2016, Kenneth M. "Elf" Sternberg.
|
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|
Created using <a href="http://sphinx-doc.org/">Sphinx</a> 1.2.2.
|
||||||
|
</div>
|
||||||
|
</body>
|
||||||
|
</html>
|
|
@ -6,7 +6,7 @@
|
||||||
<head>
|
<head>
|
||||||
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
||||||
|
|
||||||
<title>Welcome to py-polymorphic-loader’s documentation! — polyloader 0.1.0 documentation</title>
|
<title>Welcome to polyloader — polyloader 0.1.0 documentation</title>
|
||||||
|
|
||||||
<link rel="stylesheet" href="default.css" type="text/css" />
|
<link rel="stylesheet" href="default.css" type="text/css" />
|
||||||
<link rel="stylesheet" href="pygments.css" type="text/css" />
|
<link rel="stylesheet" href="pygments.css" type="text/css" />
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||||||
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@ -24,7 +24,7 @@
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<script type="text/javascript" src="underscore.js"></script>
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<script type="text/javascript" src="underscore.js"></script>
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<script type="text/javascript" src="doctools.js"></script>
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<script type="text/javascript" src="doctools.js"></script>
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<link rel="top" title="polyloader 0.1.0 documentation" href="#" />
|
<link rel="top" title="polyloader 0.1.0 documentation" href="#" />
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<link rel="next" title="<no title>" href="readme.html" />
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<link rel="next" title="Synopsis" href="readme.html" />
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<body>
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<body>
|
||||||
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|
<div class="related">
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||||||
|
@ -37,7 +37,7 @@
|
||||||
<a href="py-modindex.html" title="Python Module Index"
|
<a href="py-modindex.html" title="Python Module Index"
|
||||||
>modules</a> |</li>
|
>modules</a> |</li>
|
||||||
<li class="right" >
|
<li class="right" >
|
||||||
<a href="readme.html" title="<no title>"
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<a href="readme.html" title="Synopsis"
|
||||||
accesskey="N">next</a> |</li>
|
accesskey="N">next</a> |</li>
|
||||||
<li><a href="#">polyloader 0.1.0 documentation</a> »</li>
|
<li><a href="#">polyloader 0.1.0 documentation</a> »</li>
|
||||||
</ul>
|
</ul>
|
||||||
|
@ -48,17 +48,25 @@
|
||||||
<div class="bodywrapper">
|
<div class="bodywrapper">
|
||||||
<div class="body">
|
<div class="body">
|
||||||
|
|
||||||
<div class="section" id="welcome-to-py-polymorphic-loader-s-documentation">
|
<div class="section" id="welcome-to-polyloader">
|
||||||
<h1>Welcome to py-polymorphic-loader’s documentation!<a class="headerlink" href="#welcome-to-py-polymorphic-loader-s-documentation" title="Permalink to this headline">¶</a></h1>
|
<h1>Welcome to polyloader<a class="headerlink" href="#welcome-to-polyloader" title="Permalink to this headline">¶</a></h1>
|
||||||
<p>Contents:</p>
|
<p>Contents:</p>
|
||||||
<div class="toctree-wrapper compound">
|
<div class="toctree-wrapper compound">
|
||||||
<ul>
|
<ul>
|
||||||
|
<li class="toctree-l1"><a class="reference internal" href="readme.html">Synopsis</a></li>
|
||||||
|
<li class="toctree-l1"><a class="reference internal" href="readme.html#say-what">Say What?</a></li>
|
||||||
|
<li class="toctree-l1"><a class="reference internal" href="readme.html#what-s-the-real-problem">What’s the real problem?</a></li>
|
||||||
|
<li class="toctree-l1"><a class="reference internal" href="readme.html#what-the-solution">What the solution?</a></li>
|
||||||
<li class="toctree-l1"><a class="reference internal" href="installation.html">Installation</a><ul>
|
<li class="toctree-l1"><a class="reference internal" href="installation.html">Installation</a><ul>
|
||||||
<li class="toctree-l2"><a class="reference internal" href="installation.html#stable-release">Stable release</a></li>
|
<li class="toctree-l2"><a class="reference internal" href="installation.html#stable-release">Stable release</a></li>
|
||||||
<li class="toctree-l2"><a class="reference internal" href="installation.html#from-sources">From sources</a></li>
|
<li class="toctree-l2"><a class="reference internal" href="installation.html#from-sources">From sources</a></li>
|
||||||
</ul>
|
</ul>
|
||||||
</li>
|
</li>
|
||||||
<li class="toctree-l1"><a class="reference internal" href="usage.html">Usage</a></li>
|
<li class="toctree-l1"><a class="reference internal" href="usage.html">Usage</a></li>
|
||||||
|
<li class="toctree-l1"><a class="reference internal" href="details.html">Details on Import and Polyloader</a><ul>
|
||||||
|
<li class="toctree-l2"><a class="reference internal" href="details.html#welcome-to-the-python-import-eli5">Welcome to the Python Import ELI5!</a></li>
|
||||||
|
</ul>
|
||||||
|
</li>
|
||||||
</ul>
|
</ul>
|
||||||
</div>
|
</div>
|
||||||
</div>
|
</div>
|
||||||
|
@ -79,13 +87,13 @@
|
||||||
<div class="sphinxsidebarwrapper">
|
<div class="sphinxsidebarwrapper">
|
||||||
<h3><a href="#">Table Of Contents</a></h3>
|
<h3><a href="#">Table Of Contents</a></h3>
|
||||||
<ul>
|
<ul>
|
||||||
<li><a class="reference internal" href="#">Welcome to py-polymorphic-loader’s documentation!</a></li>
|
<li><a class="reference internal" href="#">Welcome to polyloader</a></li>
|
||||||
<li><a class="reference internal" href="#indices-and-tables">Indices and tables</a></li>
|
<li><a class="reference internal" href="#indices-and-tables">Indices and tables</a></li>
|
||||||
</ul>
|
</ul>
|
||||||
|
|
||||||
<h4>Next topic</h4>
|
<h4>Next topic</h4>
|
||||||
<p class="topless"><a href="readme.html"
|
<p class="topless"><a href="readme.html"
|
||||||
title="next chapter"><no title></a></p>
|
title="next chapter">Synopsis</a></p>
|
||||||
<h3>This Page</h3>
|
<h3>This Page</h3>
|
||||||
<ul class="this-page-menu">
|
<ul class="this-page-menu">
|
||||||
<li><a href="_sources/index.txt"
|
<li><a href="_sources/index.txt"
|
||||||
|
@ -118,7 +126,7 @@
|
||||||
<a href="py-modindex.html" title="Python Module Index"
|
<a href="py-modindex.html" title="Python Module Index"
|
||||||
>modules</a> |</li>
|
>modules</a> |</li>
|
||||||
<li class="right" >
|
<li class="right" >
|
||||||
<a href="readme.html" title="<no title>"
|
<a href="readme.html" title="Synopsis"
|
||||||
>next</a> |</li>
|
>next</a> |</li>
|
||||||
<li><a href="#">polyloader 0.1.0 documentation</a> »</li>
|
<li><a href="#">polyloader 0.1.0 documentation</a> »</li>
|
||||||
</ul>
|
</ul>
|
||||||
|
|
|
@ -25,7 +25,7 @@
|
||||||
<script type="text/javascript" src="doctools.js"></script>
|
<script type="text/javascript" src="doctools.js"></script>
|
||||||
<link rel="top" title="polyloader 0.1.0 documentation" href="index.html" />
|
<link rel="top" title="polyloader 0.1.0 documentation" href="index.html" />
|
||||||
<link rel="next" title="Usage" href="usage.html" />
|
<link rel="next" title="Usage" href="usage.html" />
|
||||||
<link rel="prev" title="<no title>" href="readme.html" />
|
<link rel="prev" title="Synopsis" href="readme.html" />
|
||||||
</head>
|
</head>
|
||||||
<body>
|
<body>
|
||||||
<div class="related">
|
<div class="related">
|
||||||
|
@ -41,7 +41,7 @@
|
||||||
<a href="usage.html" title="Usage"
|
<a href="usage.html" title="Usage"
|
||||||
accesskey="N">next</a> |</li>
|
accesskey="N">next</a> |</li>
|
||||||
<li class="right" >
|
<li class="right" >
|
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<a href="readme.html" title="<no title>"
|
<a href="readme.html" title="Synopsis"
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accesskey="P">previous</a> |</li>
|
accesskey="P">previous</a> |</li>
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||||||
<li><a href="index.html">polyloader 0.1.0 documentation</a> »</li>
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<li><a href="index.html">polyloader 0.1.0 documentation</a> »</li>
|
||||||
</ul>
|
</ul>
|
||||||
|
@ -56,8 +56,8 @@
|
||||||
<h1>Installation<a class="headerlink" href="#installation" title="Permalink to this headline">¶</a></h1>
|
<h1>Installation<a class="headerlink" href="#installation" title="Permalink to this headline">¶</a></h1>
|
||||||
<div class="section" id="stable-release">
|
<div class="section" id="stable-release">
|
||||||
<h2>Stable release<a class="headerlink" href="#stable-release" title="Permalink to this headline">¶</a></h2>
|
<h2>Stable release<a class="headerlink" href="#stable-release" title="Permalink to this headline">¶</a></h2>
|
||||||
<p>To install py-polymorphic-loader, run this command in your terminal:</p>
|
<p>To install polyloader, run this command in your terminal:</p>
|
||||||
<div class="highlight-console"><div class="highlight"><pre><span class="gp">$</span> pip install py-polymorphic-loader
|
<div class="highlight-console"><div class="highlight"><pre><span class="gp">$</span> pip install polyloader
|
||||||
</pre></div>
|
</pre></div>
|
||||||
</div>
|
</div>
|
||||||
<p>If you don’t have <a class="reference external" href="https://pip.pypa.io">pip</a> installed, this <a class="reference external" href="http://docs.python-guide.org/en/latest/starting/installation/">Python installation guide</a> can guide
|
<p>If you don’t have <a class="reference external" href="https://pip.pypa.io">pip</a> installed, this <a class="reference external" href="http://docs.python-guide.org/en/latest/starting/installation/">Python installation guide</a> can guide
|
||||||
|
@ -65,13 +65,13 @@ you through the process.</p>
|
||||||
</div>
|
</div>
|
||||||
<div class="section" id="from-sources">
|
<div class="section" id="from-sources">
|
||||||
<h2>From sources<a class="headerlink" href="#from-sources" title="Permalink to this headline">¶</a></h2>
|
<h2>From sources<a class="headerlink" href="#from-sources" title="Permalink to this headline">¶</a></h2>
|
||||||
<p>The sources for py-polymorphic-loader can be downloaded from the <a class="reference external" href="https://github.com/elfsternberg/py-polymorphic-loader">Github repo</a>.</p>
|
<p>The sources for polyloader can be downloaded from the <a class="reference external" href="https://github.com/elfsternberg/polyloader">Github repo</a>.</p>
|
||||||
<p>You can either clone the public repository:</p>
|
<p>You can either clone the public repository:</p>
|
||||||
<div class="highlight-console"><div class="highlight"><pre><span class="gp">$</span> git clone git://github.com/elfsternberg/py-polymorphic-loader
|
<div class="highlight-console"><div class="highlight"><pre><span class="gp">$</span> git clone git://github.com/elfsternberg/polyloader
|
||||||
</pre></div>
|
</pre></div>
|
||||||
</div>
|
</div>
|
||||||
<p>Or download the <a class="reference external" href="https://github.com/elfsternberg/py-polymorphic-loader/tarball/master">tarball</a>:</p>
|
<p>Or download the <a class="reference external" href="https://github.com/elfsternberg/polyloader/tarball/master">tarball</a>:</p>
|
||||||
<div class="highlight-console"><div class="highlight"><pre><span class="gp">$</span> curl -OL https://github.com/elfsternberg/py-polymorphic-loader/tarball/master
|
<div class="highlight-console"><div class="highlight"><pre><span class="gp">$</span> curl -OL https://github.com/elfsternberg/polyloader/tarball/master
|
||||||
</pre></div>
|
</pre></div>
|
||||||
</div>
|
</div>
|
||||||
<p>Once you have a copy of the source, you can install it with:</p>
|
<p>Once you have a copy of the source, you can install it with:</p>
|
||||||
|
@ -98,7 +98,7 @@ you through the process.</p>
|
||||||
|
|
||||||
<h4>Previous topic</h4>
|
<h4>Previous topic</h4>
|
||||||
<p class="topless"><a href="readme.html"
|
<p class="topless"><a href="readme.html"
|
||||||
title="previous chapter"><no title></a></p>
|
title="previous chapter">Synopsis</a></p>
|
||||||
<h4>Next topic</h4>
|
<h4>Next topic</h4>
|
||||||
<p class="topless"><a href="usage.html"
|
<p class="topless"><a href="usage.html"
|
||||||
title="next chapter">Usage</a></p>
|
title="next chapter">Usage</a></p>
|
||||||
|
@ -137,7 +137,7 @@ you through the process.</p>
|
||||||
<a href="usage.html" title="Usage"
|
<a href="usage.html" title="Usage"
|
||||||
>next</a> |</li>
|
>next</a> |</li>
|
||||||
<li class="right" >
|
<li class="right" >
|
||||||
<a href="readme.html" title="<no title>"
|
<a href="readme.html" title="Synopsis"
|
||||||
>previous</a> |</li>
|
>previous</a> |</li>
|
||||||
<li><a href="index.html">polyloader 0.1.0 documentation</a> »</li>
|
<li><a href="index.html">polyloader 0.1.0 documentation</a> »</li>
|
||||||
</ul>
|
</ul>
|
||||||
|
|
|
@ -2,6 +2,4 @@
|
||||||
# Project: polyloader
|
# Project: polyloader
|
||||||
# Version: 0.1.0
|
# Version: 0.1.0
|
||||||
# The remainder of this file is compressed using zlib.
|
# The remainder of this file is compressed using zlib.
|
||||||
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|
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j¥+Ό<>uUFς‚"…&¤Iλ:ΪΐΡΏ#$µµΟ»Δ}…ΡφD<>©~4ξ'ρ,„ήgS<67>„α‹r(Ϋ¥ΒY rΩ ΟCF®Οsb€ι^Ί¶5ζΊΒη3Ο°<CE9F>΅“^[QΞ3ςπ‚b{,ΧpήΈ<CEAE>)U«R:e΄<65>zC/3)λ<>ΩΒ+f<>"ρf$Ztή«G]ϊ~<7E>~™<1F><>ΦIΆ?¤;<3B>Y½p
|
||||||
Ă0F÷śBЬ͚t(z7V<12>l[<5B>ćöm<C3B6>K‡®ď{)°óŃᲸŽě LójBšIíŕČn!„ÆŞăŹčAKˇjF›úé]TV´ł
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';b53ÄÖaşĐ=ą‡'ÖFS<>y)š„eë†%öâ9BűU~$>f±DD7“9h”
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<title><no title> — polyloader 0.1.0 documentation</title>
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<title>Synopsis — polyloader 0.1.0 documentation</title>
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<div class="section" id="synopsis">
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<h1>Synopsis<a class="headerlink" href="#synopsis" title="Permalink to this headline">¶</a></h1>
|
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<p><strong>Polyloader</strong> is a python module that extends the Python <cite>import</cite>
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statement to enable the discovery and loading of heterogenous source
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code packages.</p>
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</div>
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<div class="section" id="say-what">
|
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|
<h1>Say What?<a class="headerlink" href="#say-what" title="Permalink to this headline">¶</a></h1>
|
||||||
|
<p>The <tt class="docutils literal"><span class="pre">import</span></tt> statement is how the Python interpreter finds a module
|
||||||
|
written in Python and loads it, turning it into variables, executable
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|
functions, constructable classes, and other Python objects, and then
|
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|
exposes those objects to the currently running program.</p>
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|
<p>The <tt class="docutils literal"><span class="pre">import</span></tt> statement has long been extensible so that things other
|
||||||
|
than Python code could be imported, but this feature has always had two
|
||||||
|
limitations:</p>
|
||||||
|
<ol class="arabic simple">
|
||||||
|
<li>It’s annoyingly hard to write an importer. (Believe me. Polyloader
|
||||||
|
<em>is</em> one!)</li>
|
||||||
|
<li>For filesystem-based modules (which is 99% of them) Python’s importer
|
||||||
|
only understands one loader type per directory. It’s not possible to
|
||||||
|
store code or data written in something other than Python in the same
|
||||||
|
directory with Python module code and load it via <tt class="docutils literal"><span class="pre">import</span></tt>.</li>
|
||||||
|
</ol>
|
||||||
|
<p>The former requires a certain degree of abstraction and thought. For
|
||||||
|
the latter, most people ignore the problem and load module configuration
|
||||||
|
files written in JSON or YAML or whatever directly. This is fine,
|
||||||
|
except when you want to write in one of Python’s extended languages like
|
||||||
|
Hy or Coconut in a framework like Django, Flask or Glitch.</p>
|
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|
<p><strong>Polyloader</strong> eliminates these limitations.</p>
|
||||||
|
</div>
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||||||
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<div class="section" id="what-s-the-real-problem">
|
||||||
|
<h1>What’s the real problem?<a class="headerlink" href="#what-s-the-real-problem" title="Permalink to this headline">¶</a></h1>
|
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|
<p>The real problem is that Python’s traditional extensions, <tt class="docutils literal"><span class="pre">.py</span></tt>,
|
||||||
|
<tt class="docutils literal"><span class="pre">.pyc/.pyo</span></tt>, and <tt class="docutils literal"><span class="pre">.so/.dll</span></tt> files, are hard-coded in Python. In
|
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|
Python 2, they’re in the <tt class="docutils literal"><span class="pre">imp</span></tt> builtin; In Python 3, they’re defined
|
||||||
|
in a private section of <cite>importlib</cite>. Either way, they’re not accessible
|
||||||
|
for modification and extension.</p>
|
||||||
|
<p>This problem is made harder by the <tt class="docutils literal"><span class="pre">pkglib</span></tt> module, which is part of
|
||||||
|
Python’s standard library. This module uses <tt class="docutils literal"><span class="pre">inspect.getmoduleinfo</span></tt>,
|
||||||
|
which again only recognizes the usual extensions. Which means you can’t
|
||||||
|
list multilingual modules either; this hampers the development of Django
|
||||||
|
management commands in a syntax other than Python.</p>
|
||||||
|
</div>
|
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|
<div class="section" id="what-the-solution">
|
||||||
|
<h1>What the solution?<a class="headerlink" href="#what-the-solution" title="Permalink to this headline">¶</a></h1>
|
||||||
|
<p>At its heart, the Python import system runs two different internal
|
||||||
|
mechanisms to figure out what the <em>import string</em> (the dotted terms
|
||||||
|
after the word “import”) “means.” Each mechanism has one or more
|
||||||
|
<em>finders</em>, and the first finder to report “I have a <em>loader</em> that knows
|
||||||
|
what that import string means” wins.</p>
|
||||||
|
<p>The very last finder is for the filesystem. The solution is to get in
|
||||||
|
front of that finder with one that can handle all the other syntax
|
||||||
|
loaders <em>and</em> knows how to fall back on the last one for those files the
|
||||||
|
last one handles.</p>
|
||||||
|
<p>That’s what <tt class="docutils literal"><span class="pre">polyloader</span></tt> does.</p>
|
||||||
|
</div>
|
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|
||||||
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<h3><a href="index.html">Table Of Contents</a></h3>
|
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<ul>
|
||||||
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<li><a class="reference internal" href="#">Synopsis</a></li>
|
||||||
|
<li><a class="reference internal" href="#say-what">Say What?</a></li>
|
||||||
|
<li><a class="reference internal" href="#what-s-the-real-problem">What’s the real problem?</a></li>
|
||||||
|
<li><a class="reference internal" href="#what-the-solution">What the solution?</a></li>
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</ul>
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||||||
<h4>Previous topic</h4>
|
<h4>Previous topic</h4>
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<p class="topless"><a href="index.html"
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<p class="topless"><a href="index.html"
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title="previous chapter">Welcome to py-polymorphic-loader’s documentation!</a></p>
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title="previous chapter">Welcome to polyloader</a></p>
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<h4>Next topic</h4>
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<h4>Next topic</h4>
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<p class="topless"><a href="installation.html"
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<p class="topless"><a href="installation.html"
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title="next chapter">Installation</a></p>
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<a href="installation.html" title="Installation"
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<a href="index.html" title="Welcome to py-polymorphic-loader’s documentation!"
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<a href="index.html" title="Welcome to polyloader"
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>previous</a> |</li>
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>previous</a> |</li>
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<li><a href="index.html">polyloader 0.1.0 documentation</a> »</li>
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<li><a href="index.html">polyloader 0.1.0 documentation</a> »</li>
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Search.setIndex({envversion:42,terms:{compil:[7,8],set:8,suffix:[7,8],creat:8,process:1,onc:1,modul:[0,2],automat:8,pip:1,through:1,have:1,instal:0,tarbal:1,stabl:0,download:1,guid:1,assum:8,your:1,page:0,index:0,git:1,from:0,activ:8,content:[0,2],leav:8,which:8,master:1,you:1,"public":1,can:1,elfsternberg:1,setup:1,sourc:0,run:[8,1],thi:1,python:[8,1],usag:0,clone:1,copi:1,upon:8,curl:1,standard:8,repo:1,releas:0,mechan:8,repositori:1,termin:1,pair:8,don:1,reset:7,search:0,github:1,last:8,packag:2,remov:8,current:8,http:1,manag:8,project:6,instanc:8,command:1,either:1,context:8,lifetim:8,com:1,scope:8,"import":6},objtypes:{"0":"py:module","1":"py:function"},objnames:{"0":["py","module","Python module"],"1":["py","function","Python function"]},filenames:["index","installation","modules","contributing","readme","authors","usage","polyloader","todo","history"],titles:["Welcome to py-polymorphic-loader’s documentation!","Installation","polyloader","<no title>","<no title>","<no title>","Usage","polyloader package","<no title>","<no title>"],objects:{"":{polyloader:[7,0,0,"-"]},polyloader:{reset:[7,1,1,""],install:[7,1,1,""]}},titleterms:{polymorph:0,sourc:1,from:1,welcom:0,modul:7,usag:6,indic:0,loader:0,content:7,packag:7,polyload:[7,2],tabl:0,releas:1,stabl:1,document:0,instal:1}})
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|
||||||
|
Details on Import and Polyloader
|
||||||
|
================================
|
||||||
|
|
||||||
|
Welcome to the Python Import ELI5!
|
||||||
|
**********************************
|
||||||
|
|
||||||
|
What is `import`?
|
||||||
|
-----------------
|
||||||
|
|
||||||
|
``import`` is a Python statement that finds a *module* that is accessible
|
||||||
|
by the currently running process, loads it, and makes its contents
|
||||||
|
available to the scope in which the statement was made. A statement
|
||||||
|
like
|
||||||
|
|
||||||
|
``import django.db.models``
|
||||||
|
|
||||||
|
is looking for a module named ``django.db.models``. If the statement is
|
||||||
|
successful, ``django.db.models`` will be a variable name in the scope,
|
||||||
|
it will be a Python *object* (of ``class Module``, but that's not
|
||||||
|
important), and it will have functions, class constructors, variables
|
||||||
|
and constants. These Python objects will be accessible through the dot
|
||||||
|
operator.
|
||||||
|
|
||||||
|
An alternative way of writing import statements is
|
||||||
|
|
||||||
|
``from django.utils import encoding``
|
||||||
|
|
||||||
|
And then the variable will just be ``encoding``. The ``encoding``
|
||||||
|
module has a function for handling unicode-to-web translation.
|
||||||
|
Accessing it through the dot operator, it looks like this:
|
||||||
|
|
||||||
|
``ready_str = encoding.smart_str(unready_str)``
|
||||||
|
|
||||||
|
We call the parts of the import statement that describe the module the
|
||||||
|
*import string*.
|
||||||
|
|
||||||
|
``sys.path_hooks``: How does Python know where to look?
|
||||||
|
-------------------------------------------------------
|
||||||
|
|
||||||
|
That's what's funny. Python has two independent ways of making sense of
|
||||||
|
of the import string. The old system is based on the assumption that
|
||||||
|
everything is a filesystem, with folders and filenames. This is called
|
||||||
|
the ``sys.path_hooks`` system.
|
||||||
|
|
||||||
|
In the old system, the parts of the import string would be split up, and
|
||||||
|
then a collection of directories would be scanned to see if the first
|
||||||
|
name in the import string could be matched with a subdirectory. If it
|
||||||
|
could, that directory would be scanned until the last name on the import
|
||||||
|
string. If that name was a *filename*, it would be loaded as a module.
|
||||||
|
If that name was a *directory* and that directory had a file named
|
||||||
|
``__init__.py``, then that file would be loaded as the module.
|
||||||
|
|
||||||
|
The ``sys.path_hooks`` array has a list of different methods for trying to
|
||||||
|
scan a filesystem for the parts of the import string. A ``path_hook`` is
|
||||||
|
a function that takes a path to a directory; if it can handle the
|
||||||
|
contents of the directory, it returns a **Finder**, an object whose job
|
||||||
|
is to figure out how to load the module; if it can't, it returns an
|
||||||
|
ImportError exception. The object that loads the module is called,
|
||||||
|
naturally, a **Loader**.
|
||||||
|
|
||||||
|
* To read more about **Finders**, see :ref:`eli5-finders`
|
||||||
|
* To read more about **Loaders**, see :ref:`eli5-loaders`
|
||||||
|
* To read more about **Path Hooks**, see :ref:`eli5-pathhooks`
|
||||||
|
|
||||||
|
``sys.path``: What directories are searched?
|
||||||
|
--------------------------------------------
|
||||||
|
|
||||||
|
The list of directories is stored in an array, ``sys.path``. This path is
|
||||||
|
initialized by Python when it starts up, but programs can modify it at
|
||||||
|
run-time to point to extra directories if they want.
|
||||||
|
|
||||||
|
|
||||||
|
``sys.meta_path``: What is the new system?
|
||||||
|
------------------------------------------
|
||||||
|
|
||||||
|
The new system is called ``sys.meta_path``, and it's an array of
|
||||||
|
**Finders**, objects that have one method, ``find_module(fullname)``.
|
||||||
|
It's an anything-goes API that gives developers the freedom to import
|
||||||
|
modules from anywhere: databases, archives, remote web resources, even
|
||||||
|
code written on-the-fly internally. The new system can apply any
|
||||||
|
meaning at all to the import string.
|
||||||
|
|
||||||
|
In Python, the import string is offered to each object in
|
||||||
|
``sys.meta_path`` before being offered to each ``sys.path_hook``. The
|
||||||
|
filesystem is typically the last finder tried.
|
||||||
|
|
||||||
|
To read more about **Meta Paths**, see :ref:`eli5-metapaths`
|
||||||
|
|
||||||
|
Is it different between Python 2 and Python 3?
|
||||||
|
---------------------------------------------
|
||||||
|
|
||||||
|
Python 3 moves almost everything about this process into python's
|
||||||
|
library, leaving only a bare minimum of functionality inside the Python
|
||||||
|
executable to load this library and run it. When the Python developers
|
||||||
|
did that, they added a lot of functionality to make it easier to write
|
||||||
|
new import modules. The old way still works, but there are now *Module
|
||||||
|
Specifications*, which are metadata about a module, and the old
|
||||||
|
``path_hooks`` system is now just a ``meta_path`` handler added to the
|
||||||
|
new system as the last resort.
|
||||||
|
|
||||||
|
To read more about **Module Specifications**, see :ref:`eli5-specs`
|
||||||
|
|
||||||
|
Does the old system still matter?
|
||||||
|
---------------------------------
|
||||||
|
|
||||||
|
Yes, for one reason: *iteration*. Iteration is the ability to take a
|
||||||
|
path where you believe Python modules can be found, and list through
|
||||||
|
them. This facility is useful for large frameworks where a user wants
|
||||||
|
to add new commands, or new objects, or new operations; Django uses this
|
||||||
|
facility a lot! The ``pkgutil`` library depends upon Finders being able
|
||||||
|
to iterate their contents.
|
|
@ -0,0 +1,37 @@
|
||||||
|
ELI5: Explain Like I'm Five!
|
||||||
|
============================
|
||||||
|
|
||||||
|
.. _eli5-finders:
|
||||||
|
|
||||||
|
Finders
|
||||||
|
=======
|
||||||
|
|
||||||
|
TODO
|
||||||
|
|
||||||
|
.. _eli5-loaders:
|
||||||
|
|
||||||
|
Loaders
|
||||||
|
=======
|
||||||
|
|
||||||
|
TODO
|
||||||
|
|
||||||
|
.. _eli5-pathhooks:
|
||||||
|
|
||||||
|
Path Hooks
|
||||||
|
==========
|
||||||
|
|
||||||
|
TODO
|
||||||
|
|
||||||
|
.. _eli5-metapaths:
|
||||||
|
|
||||||
|
Meta Paths
|
||||||
|
==========
|
||||||
|
|
||||||
|
TODO
|
||||||
|
|
||||||
|
.. _eli5-specs:
|
||||||
|
|
||||||
|
Module Specifications
|
||||||
|
=====================
|
||||||
|
|
||||||
|
TODO
|
|
@ -3,8 +3,8 @@
|
||||||
You can adapt this file completely to your liking, but it should at least
|
You can adapt this file completely to your liking, but it should at least
|
||||||
contain the root `toctree` directive.
|
contain the root `toctree` directive.
|
||||||
|
|
||||||
Welcome to py-polymorphic-loader's documentation!
|
Welcome to polyloader
|
||||||
======================================
|
=====================
|
||||||
|
|
||||||
Contents:
|
Contents:
|
||||||
|
|
||||||
|
@ -14,6 +14,7 @@ Contents:
|
||||||
readme
|
readme
|
||||||
installation
|
installation
|
||||||
usage
|
usage
|
||||||
|
details
|
||||||
contributing
|
contributing
|
||||||
authors
|
authors
|
||||||
history
|
history
|
||||||
|
|
|
@ -8,11 +8,11 @@ Installation
|
||||||
Stable release
|
Stable release
|
||||||
--------------
|
--------------
|
||||||
|
|
||||||
To install py-polymorphic-loader, run this command in your terminal:
|
To install polyloader, run this command in your terminal:
|
||||||
|
|
||||||
.. code-block:: console
|
.. code-block:: console
|
||||||
|
|
||||||
$ pip install py-polymorphic-loader
|
$ pip install polyloader
|
||||||
|
|
||||||
If you don't have `pip`_ installed, this `Python installation guide`_ can guide
|
If you don't have `pip`_ installed, this `Python installation guide`_ can guide
|
||||||
you through the process.
|
you through the process.
|
||||||
|
@ -24,19 +24,19 @@ you through the process.
|
||||||
From sources
|
From sources
|
||||||
------------
|
------------
|
||||||
|
|
||||||
The sources for py-polymorphic-loader can be downloaded from the `Github repo`_.
|
The sources for polyloader can be downloaded from the `Github repo`_.
|
||||||
|
|
||||||
You can either clone the public repository:
|
You can either clone the public repository:
|
||||||
|
|
||||||
.. code-block:: console
|
.. code-block:: console
|
||||||
|
|
||||||
$ git clone git://github.com/elfsternberg/py-polymorphic-loader
|
$ git clone git://github.com/elfsternberg/polyloader
|
||||||
|
|
||||||
Or download the `tarball`_:
|
Or download the `tarball`_:
|
||||||
|
|
||||||
.. code-block:: console
|
.. code-block:: console
|
||||||
|
|
||||||
$ curl -OL https://github.com/elfsternberg/py-polymorphic-loader/tarball/master
|
$ curl -OL https://github.com/elfsternberg/polyloader/tarball/master
|
||||||
|
|
||||||
Once you have a copy of the source, you can install it with:
|
Once you have a copy of the source, you can install it with:
|
||||||
|
|
||||||
|
@ -45,5 +45,5 @@ Once you have a copy of the source, you can install it with:
|
||||||
$ python setup.py install
|
$ python setup.py install
|
||||||
|
|
||||||
|
|
||||||
.. _Github repo: https://github.com/elfsternberg/py-polymorphic-loader
|
.. _Github repo: https://github.com/elfsternberg/polyloader
|
||||||
.. _tarball: https://github.com/elfsternberg/py-polymorphic-loader/tarball/master
|
.. _tarball: https://github.com/elfsternberg/polyloader/tarball/master
|
||||||
|
|
|
@ -1 +1 @@
|
||||||
.. include:: ../README.rst
|
.. include:: ../../README.rst
|
||||||
|
|
|
@ -2,6 +2,21 @@
|
||||||
Usage
|
Usage
|
||||||
=====
|
=====
|
||||||
|
|
||||||
To use py-polymorphic-loader in a project::
|
Import polyloader in your python script's launcher or library, as well
|
||||||
|
as the syntax compiler(s) you plan to use. For example, if you have
|
||||||
|
`Mochi <https://github.com/i2y/mochi>`__ and `Hy
|
||||||
|
<http://docs.hylang.org/en/latest/>`__ installed, and you wanted to
|
||||||
|
write a Django app, edit manage.py and add the following lines at the
|
||||||
|
top:
|
||||||
|
|
||||||
|
::
|
||||||
|
|
||||||
|
from mochi.main import compile_file as mochi_compile
|
||||||
|
from hy.importer import ast_compile as hy_compile
|
||||||
|
import polyloader
|
||||||
|
polyloader.install(mochi_compile, ['.mochi'])
|
||||||
|
polyloader.install(hy_compile, ['.hy'])}
|
||||||
|
|
||||||
|
Now your views can be written in Hy and your models in Mochi, and
|
||||||
|
everything will just work.
|
||||||
|
|
||||||
import py-polymorphic-loader
|
|
||||||
|
|
|
@ -24,7 +24,7 @@
|
||||||
<script type="text/javascript" src="underscore.js"></script>
|
<script type="text/javascript" src="underscore.js"></script>
|
||||||
<script type="text/javascript" src="doctools.js"></script>
|
<script type="text/javascript" src="doctools.js"></script>
|
||||||
<link rel="top" title="polyloader 0.1.0 documentation" href="index.html" />
|
<link rel="top" title="polyloader 0.1.0 documentation" href="index.html" />
|
||||||
<link rel="next" title="<no title>" href="contributing.html" />
|
<link rel="next" title="Details on Import and Polyloader" href="details.html" />
|
||||||
<link rel="prev" title="Installation" href="installation.html" />
|
<link rel="prev" title="Installation" href="installation.html" />
|
||||||
</head>
|
</head>
|
||||||
<body>
|
<body>
|
||||||
|
@ -38,7 +38,7 @@
|
||||||
<a href="py-modindex.html" title="Python Module Index"
|
<a href="py-modindex.html" title="Python Module Index"
|
||||||
>modules</a> |</li>
|
>modules</a> |</li>
|
||||||
<li class="right" >
|
<li class="right" >
|
||||||
<a href="contributing.html" title="<no title>"
|
<a href="details.html" title="Details on Import and Polyloader"
|
||||||
accesskey="N">next</a> |</li>
|
accesskey="N">next</a> |</li>
|
||||||
<li class="right" >
|
<li class="right" >
|
||||||
<a href="installation.html" title="Installation"
|
<a href="installation.html" title="Installation"
|
||||||
|
@ -54,10 +54,20 @@
|
||||||
|
|
||||||
<div class="section" id="usage">
|
<div class="section" id="usage">
|
||||||
<h1>Usage<a class="headerlink" href="#usage" title="Permalink to this headline">¶</a></h1>
|
<h1>Usage<a class="headerlink" href="#usage" title="Permalink to this headline">¶</a></h1>
|
||||||
<p>To use py-polymorphic-loader in a project:</p>
|
<p>Import polyloader in your python script’s launcher or library, as well
|
||||||
<div class="highlight-python"><div class="highlight"><pre>import py-polymorphic-loader
|
as the syntax compiler(s) you plan to use. For example, if you have
|
||||||
|
<a class="reference external" href="https://github.com/i2y/mochi">Mochi</a> and <a class="reference external" href="http://docs.hylang.org/en/latest/">Hy</a> installed, and you wanted to
|
||||||
|
write a Django app, edit manage.py and add the following lines at the
|
||||||
|
top:</p>
|
||||||
|
<div class="highlight-python"><div class="highlight"><pre>from mochi.main import compile_file as mochi_compile
|
||||||
|
from hy.importer import ast_compile as hy_compile
|
||||||
|
import polyloader
|
||||||
|
polyloader.install(mochi_compile, ['.mochi'])
|
||||||
|
polyloader.install(hy_compile, ['.hy'])}
|
||||||
</pre></div>
|
</pre></div>
|
||||||
</div>
|
</div>
|
||||||
|
<p>Now your views can be written in Hy and your models in Mochi, and
|
||||||
|
everything will just work.</p>
|
||||||
</div>
|
</div>
|
||||||
|
|
||||||
|
|
||||||
|
@ -70,8 +80,8 @@
|
||||||
<p class="topless"><a href="installation.html"
|
<p class="topless"><a href="installation.html"
|
||||||
title="previous chapter">Installation</a></p>
|
title="previous chapter">Installation</a></p>
|
||||||
<h4>Next topic</h4>
|
<h4>Next topic</h4>
|
||||||
<p class="topless"><a href="contributing.html"
|
<p class="topless"><a href="details.html"
|
||||||
title="next chapter"><no title></a></p>
|
title="next chapter">Details on Import and Polyloader</a></p>
|
||||||
<h3>This Page</h3>
|
<h3>This Page</h3>
|
||||||
<ul class="this-page-menu">
|
<ul class="this-page-menu">
|
||||||
<li><a href="_sources/usage.txt"
|
<li><a href="_sources/usage.txt"
|
||||||
|
@ -104,7 +114,7 @@
|
||||||
<a href="py-modindex.html" title="Python Module Index"
|
<a href="py-modindex.html" title="Python Module Index"
|
||||||
>modules</a> |</li>
|
>modules</a> |</li>
|
||||||
<li class="right" >
|
<li class="right" >
|
||||||
<a href="contributing.html" title="<no title>"
|
<a href="details.html" title="Details on Import and Polyloader"
|
||||||
>next</a> |</li>
|
>next</a> |</li>
|
||||||
<li class="right" >
|
<li class="right" >
|
||||||
<a href="installation.html" title="Installation"
|
<a href="installation.html" title="Installation"
|
||||||
|
|
Loading…
Reference in New Issue