[Python-checkins] r56970 - sandbox/trunk/import_in_py/_importlib.py

[brett.cannon]

Author: brett.cannon
Date: Mon Aug 13 02:30:14 2007
New Revision: 56970

Modified:
   sandbox/trunk/import_in_py/_importlib.py
Log:
An untested, initial pass at making file system importers more modular.


Modified: sandbox/trunk/import_in_py/_importlib.py
==============================================================================
--- sandbox/trunk/import_in_py/_importlib.py	(original)
+++ sandbox/trunk/import_in_py/_importlib.py	Mon Aug 13 02:30:14 2007
@@ -239,6 +239,80 @@
             raise ImportError("can only handle directories")
 
 
+class FileImporter(object):
+
+    """Base class for file importers.
+
+    Subclasses are expected to define the following attributes:
+
+    * _file_types
+        Sequence of imp file types (e.g., imp.C_EXTENSION).
+    * _possible_package
+        True if importer should check for packages.
+    * _loader
+        A callable that takes the found file path to the requested module and
+        returns a loader for the module found at that path.
+
+    """
+
+    def __init__(self, path_entry):
+        """Initialize an importer for the passed-in sys.path entry (which is
+        assumed to have already been verified as an existing directory).
+
+        Can be used as an entry on sys.path_hook.
+
+        """
+        self._path_entry = path_entry
+        # XXX Worth pre-calculating in a metaclass?
+        self._suffixes = [suffix[0] for suffix in imp.get_suffixes()
+                            if suffix[2] in self._file_types]
+
+    def find_module(self, fullname, path=None):
+        tail_module = name.rsplit('.', 1)[-1]
+        # XXX Do we need to check for packages first with all possible file
+        #     extensions and then check for files?
+        for ext in self._suffixes:
+            if self._possible_package:
+                package_directory = _path_join(self._path_entry, tail_module)
+                init_filename = '__init__' + ext
+                package_init = _path_join(package_directory, init_filename)
+                if (_path_isfile(package_init) and
+                        _case_ok(self._path_entry, tail_module) and
+                        _case_ok(package_directory, init_filename)):
+                    return self._loader(package_init)
+            file_name = tail_module + ext
+            file_path = _path_join(self._path_entry, file_name)
+            if (_path_isfile(file_path) and
+                    _case_ok(self._path_entry, file_name)):
+                return self._loader(file_path)
+        else:
+            # Raise a warning if it matches a directory w/o an __init__ file.
+            if (_path_isdir(package_directory) and
+                    _case_ok(self._path_entry, tail_module)):
+                warnings.warn("Not importing directory %s: missing __init__"
+                                    % package_directory,
+                                ImportWarning)
+            return None
+
+
+class ExtensionFileImporter(FileImporter):
+
+    """Importer for extension files."""
+
+    _file_types = [imp.C_EXTENSION]
+    _possible_package = False
+    _loader = ExtensionFileLoader
+
+
+class PyFileImporter(FileImporter):
+
+    """Importer for source/bytecode files."""
+
+    _file_types = [imp.PY_SOURCE, imp.PY_COMPILED]
+    _possible_package = True
+    _loader = PyFileLoader
+
+
 class FileSystemImporter(object):
 
     """Importer for the filesystem using the passed-in handlers."""