Heading toward a final draft of the Py-2 instances.
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README.rst
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README.rst
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@ -11,24 +11,24 @@ Problem Statement
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The Python module loader system is hard-coded to prevent the discovery
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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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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 allowed
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current (as of this writing) Python 3.5, the import mechanism allows for
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for the creation of file finders and importers that would transform
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the creation of file finders and importers that would transform Python's
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Python's import syntax into a *path,* assert whether or not that path
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import syntax into a *path,* assert whether or not that path could be
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could be made to correspond to a *syntax object*, and then attempt to
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made to correspond to a *syntax object*, and then attempt to *load* that
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*load* that syntax object as a Python module. Python *packages*,
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syntax object as a Python module. Python *packages*, however, are
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however, are assumed to be uniformly made up of Python syntax objects,
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assumed to be uniformly made up of Python syntax objects, be they
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be they **.py** source files, **.pyc/.pyo** bytecode, or **.so/.dll**
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**.py** source files, **.pyc/.pyo** bytecode, or **.so/.dll** files with
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files with an exposed Python-to-C API. In Python 2 these suffixes are
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an exposed Python-to-C API. In Python 2 these suffixes are hard-coded
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hard-coded into the source in the **imp** builtin module; in Python 3
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into the source in the **imp** builtin module; in Python 3 these
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these suffixes are constants defined in a private section of
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suffixes are constants defined in a private section of **importlib**; in
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**importlib**; in either case, they are unavailable for modification.
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either case, they are unavailable for modification. This lack of access
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This lack of access to the extensions list prevents the *discovery* of
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to the extensions list prevents the *discovery* of heterogenous source
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heterogenous source code packages.
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code packages.
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The discovery mechanism is outlined in Python's pkgutil module; features
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The discovery mechanism is outlined in Python's **pkgutil** module;
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such as **pkgutil.iter_modules** do not work with heterogenous source
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features such as **pkgutil.iter_modules** do not work with heterogenous
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code, which in turn means that one cannot write, for one important
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source code, which in turn means that one cannot write, for one
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example, Django management commands in an alternative syntax.
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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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**polyloader** is a python module that intercepts calls to the default
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finder, loader, and package module iterator, and if the path resolves to
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finder, loader, and package module iterator, and if the path resolves to
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@ -5,10 +5,10 @@ __author__ = 'Kenneth M. "Elf" Sternberg'
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__email__ = 'elf.sternberg@gmail.com'
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__email__ = 'elf.sternberg@gmail.com'
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__version__ = '0.1.0'
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__version__ = '0.1.0'
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if sys.version[0:2] == (2, 7):
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if sys.version_info[0:2] >= (2, 6):
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from ._python27 import install
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from ._python2 import install
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if sys.version[0] >= 3:
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if sys.version_info[0] >= 3:
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from ._python3 import install
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from ._python3 import install
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__all__ = ['install']
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__all__ = ['install']
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@ -64,34 +64,41 @@ class PolyLoader(pkgutil.ImpLoader):
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# the iter_modules; or we provide our own finder and ensure it gets
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# the iter_modules; or we provide our own finder and ensure it gets
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# found before the native one.
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# found before the native one.
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We actually want to have multiple
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# Why the heck python 2.6 insists on calling finders "importers" is
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# SourceFileFinders, each of which either recognizes the file to be
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# beyond me. At least in calls loaders "loaders".
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class PolyFinder(object):
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class PolyFinder(object):
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def __init__(self, path = None):
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def __init__(self, path = None):
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self.path = path
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self.path = path
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def find_on_path(self, fullname):
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def _pl_find_on_path(self, fullname, path=None):
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fls = ["%s/__init__.%s", "%s.%s"]
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subname = fullname.split(".")[-1]
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dirpath = "/".join(fullname.split("."))
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if subname != fullname and self.path is None:
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return None
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# As in the original, we ignore the 'path' argument
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path = None
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if self.path is not None:
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path = [os.path.realpath(self.path)]
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for pth in sys.path:
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fls = ["%s/__init__.%s", "%s.%s"]
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pth = os.path.abspath(pth)
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for fp in fls:
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for fp in fls:
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for (compiler, suffix) in PolyLoader._loader_handlers:
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for (compiler, suffix) in PolyLoader._loader_handlers:
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composed_path = fp % ("%s/%s" % (pth, dirpath), suffix)
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composed_path = fp % ("%s/%s" % (pth, dirpath), suffix)
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if os.path.exists(composed_path):
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if os.path.exists(composed_path):
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return composed_path
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return PolyLoader(composed_path)
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try:
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file, filename, etc = imp.find_module(subname, path)
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except ImportError:
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return None
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return ImpLoader(fullname, file, filename, etc)
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def find_module(self, fullname, path=None):
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def find_module(self, fullname, path=None):
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path = self.find_on_path(fullname)
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path = self._pl_find_on_path(fullname)
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if path:
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if path:
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return PolyLoader(path)
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return PolyLoader(path)
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return None
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def _install(compiler, suffixes):
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def _install(compiler, suffixes):
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sys.meta_path.insert(0, MetaImporter())
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sys.meta_path.insert(0, MetaImporter())
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iter_importer_modules.register(MetaImporter, meta_iterate_modules)
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iter_importer_modules.register(MetaImporter, meta_iterate_modules)
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