zipextimporter.py

r"""zipextimporter - an importer which can import extension modules from zipfiles

This file and also _memimporter.pyd is part of the py2exe package.

Overview
========

zipextimporter.py contains the ZipExtImporter class which allows to
load Python binary extension modules contained in a zip.archive,
without unpacking them to the file system.

Call the zipextimporter.install() function to install the import hook,
add a zip-file containing .pyd or .dll extension modules to sys.path,
and import them.

It uses the _memimporter extension which uses code from Joachim
Bauch's MemoryModule library.  This library emulates the win32 api
function LoadLibrary.

Sample usage
============

You have to prepare a zip-archive 'lib.zip' containing
your Python's _socket.pyd for this example to work.

>>> import zipextimporter
>>> zipextimporter.install()
>>> import sys
>>> sys.path.insert(0, "lib.zip")
>>> import _socket
>>> print _socket
<module '_socket' from 'lib.zip\_socket.pyd'>
>>> _socket.__file__
'lib.zip\\_socket.pyd'
>>> _socket.__loader__
<ZipExtensionImporter object 'lib.zip'>
>>> # Reloading also works correctly:
>>> _socket is reload(_socket)
True
>>>

"""
import imp, sys
import zipimport
import _memimporter

class ZipExtensionImporter(zipimport.zipimporter):
    _suffixes = [s[0] for s in imp.get_suffixes() if s[2] == imp.C_EXTENSION]

    def find_module(self, fullname, path=None):
        result = zipimport.zipimporter.find_module(self, fullname, path)
        if result:
            return result
        if fullname in ("pywintypes", "pythoncom"):
            fullname = fullname + "%d%d" % sys.version_info[:2]
            fullname = fullname.replace(".", "\\") + ".dll"
            if fullname in self._files:
                return self
        else:
            fullname = fullname.replace(".", "\\")
            for s in self._suffixes:
                if (fullname + s) in self._files:
                    return self
        return None

    def locate_dll_image(self, name):
        # A callback function for_memimporter.import_module.  Tries to
        # locate additional dlls.  Returns the image as Python string,
        # or None if not found.
        if name in self._files:
            return self.get_data(name)
        return None

    def load_module(self, fullname):
        if sys.modules.has_key(fullname):
            mod = sys.modules[fullname]
            if _memimporter.get_verbose_flag():
                sys.stderr.write("import %s # previously loaded from zipfile %s\n" % (fullname, self.archive))
            return mod
        _memimporter.set_find_proc(self.locate_dll_image)
        try:
            return zipimport.zipimporter.load_module(self, fullname)
        except zipimport.ZipImportError:
            pass
        initname = "init" + fullname.split(".")[-1] # name of initfunction
        filename = fullname.replace(".", "\\")
        if filename in ("pywintypes", "pythoncom"):
            filename = filename + "%d%d" % sys.version_info[:2]
            suffixes = ('.dll',)
        else:
            suffixes = self._suffixes
        for s in suffixes:
            path = filename + s
            if path in self._files:
                if _memimporter.get_verbose_flag():
                    sys.stderr.write("# found %s in zipfile %s\n" % (path, self.archive))
                code = self.get_data(path)
                mod = _memimporter.import_module(code, initname, fullname, path)
                mod.__file__ = "%s\\%s" % (self.archive, path)
                mod.__loader__ = self
                if _memimporter.get_verbose_flag():
                    sys.stderr.write("import %s # loaded from zipfile %s\n" % (fullname, mod.__file__))
                return mod
        raise zipimport.ZipImportError, "can't find module %s" % fullname

    def __repr__(self):
        return "<%s object %r>" % (self.__class__.__name__, self.archive)

def install():
    "Install the zipextimporter"
    sys.path_hooks.insert(0, ZipExtensionImporter)
    sys.path_importer_cache.clear()

##if __name__ == "__main__":
##    import doctest
##    doctest.testmod()