Adding basic imputil documentation.

Doc/library/imputil.rst

+
+:mod:`imputil` --- Import utilities
+=====================================================
+
+.. module:: imputil
+   :synopsis: Manage and augment the import process
+
+
+.. index:: statement: import
+
+This module provides a very handy and useful mechanism for custom
+:keyword:`import` hooks. Compared to the standard library's ihooks.py,
+imputil.py takes a dramatically simpler and more straight-forward approach
+to custom :keyword:`import` functions.
+
+
+.. class:: ImportManager([fs_imp])
+
+   Manage the import process.
+
+   .. method:: ImportManager.install([namespace])
+
+      Install this ImportManager into the specified namespace.
+
+   .. method:: ImportManager.uninstall()
+
+      Restore the previous import mechanism.
+
+   .. method:: ImportManager.add_suffix(suffix, importFunc)
+
+      Undocumented.
+
+
+.. class:: Importer()
+
+   Base class for replacing standard import functions.
+
+   .. method:: Importer.import_top(name)
+
+      Import a top-level module.
+
+   .. method:: Importer.get_code(parent, modname, fqname)
+
+      Find and retrieve the code for the given module.
+
+      parent specifies a parent module to define a context for importing. It
+      may be None, indicating no particular context for the search.
+
+      modname specifies a single module (not dotted) within the parent.
+
+      fqname specifies the fully-qualified module name. This is a
+      (potentially) dotted name from the "root" of the module namespace
+      down to the modname.
+
+      If there is no parent, then modname==fqname.
+
+      This method should return None, or a 3-tuple.
+
+        * If the module was not found, then None should be returned.
+
+        * The first item of the 2- or 3-tuple should be the integer 0 or 1,
+            specifying whether the module that was found is a package or not.
+
+        * The second item is the code object for the module (it will be
+            executed within the new module's namespace). This item can also
+            be a fully-loaded module object (e.g. loaded from a shared lib).
+
+        * The third item is a dictionary of name/value pairs that will be
+            inserted into new module before the code object is executed. This
+            is provided in case the module's code expects certain values (such
+            as where the module was found). When the second item is a module
+            object, then these names/values will be inserted *after* the module
+            has been loaded/initialized.
+
+
+.. class:: BuiltinImporter()
+
+   Emulate the import mechanism for builtin and frozen modules.  This is a
+   sub-class of the Importer module.
+
+   .. method:: BuiltinImporter.get_code(parent, modname, fqname)
+
+      Undocumented.
+
+.. function:: py_suffix_importer(filename, finfo, fqname)
+
+   Undocumented.
+
+.. class:: DynLoadSuffixImporter([desc])
+
+   Undocumented.
+
+   .. method:: DynLoadSuffixImporter.import_file(filename, finfo, fqname)
+
+      Undocumented.
+
+.. _examples-imputil:
+
+Examples
+--------
+
+This is a re-implementation of hierarchical module import.
+
+This code is intended to be read, not executed.  However, it does work
+-- all you need to do to enable it is "import knee".
+
+(The name is a pun on the klunkier predecessor of this module, "ni".)
+
+
+   import sys, imp, __builtin__
+
+   # Replacement for __import__()
+   def import_hook(name, globals=None, locals=None, fromlist=None):
+       parent = determine_parent(globals)
+       q, tail = find_head_package(parent, name)
+       m = load_tail(q, tail)
+       if not fromlist:
+           return q
+       if hasattr(m, "__path__"):
+           ensure_fromlist(m, fromlist)
+       return m
+
+   def determine_parent(globals):
+       if not globals or  not globals.has_key("__name__"):
+           return None
+       pname = globals['__name__']
+       if globals.has_key("__path__"):
+           parent = sys.modules[pname]
+           assert globals is parent.__dict__
+           return parent
+       if '.' in pname:
+           i = pname.rfind('.')
+           pname = pname[:i]
+           parent = sys.modules[pname]
+           assert parent.__name__ == pname
+           return parent
+       return None
+
+   def find_head_package(parent, name):
+       if '.' in name:
+           i = name.find('.')
+           head = name[:i]
+           tail = name[i+1:]
+       else:
+           head = name
+           tail = ""
+       if parent:
+           qname = "%s.%s" % (parent.__name__, head)
+       else:
+           qname = head
+       q = import_module(head, qname, parent)
+       if q: return q, tail
+       if parent:
+           qname = head
+           parent = None
+           q = import_module(head, qname, parent)
+           if q: return q, tail
+       raise ImportError, "No module named " + qname
+
+   def load_tail(q, tail):
+       m = q
+       while tail:
+           i = tail.find('.')
+           if i < 0: i = len(tail)
+           head, tail = tail[:i], tail[i+1:]
+           mname = "%s.%s" % (m.__name__, head)
+           m = import_module(head, mname, m)
+           if not m:
+               raise ImportError, "No module named " + mname
+       return m
+
+   def ensure_fromlist(m, fromlist, recursive=0):
+       for sub in fromlist:
+           if sub == "*":
+               if not recursive:
+                   try:
+                       all = m.__all__
+                   except AttributeError:
+                       pass
+                   else:
+                       ensure_fromlist(m, all, 1)
+               continue
+           if sub != "*" and not hasattr(m, sub):
+               subname = "%s.%s" % (m.__name__, sub)
+               submod = import_module(sub, subname, m)
+               if not submod:
+                   raise ImportError, "No module named " + subname
+
+   def import_module(partname, fqname, parent):
+       try:
+           return sys.modules[fqname]
+       except KeyError:
+           pass
+       try:
+           fp, pathname, stuff = imp.find_module(partname,
+                                                 parent and parent.__path__)
+       except ImportError:
+           return None
+       try:
+           m = imp.load_module(fqname, fp, pathname, stuff)
+       finally:
+           if fp: fp.close()
+       if parent:
+           setattr(parent, partname, m)
+       return m
+
+
+   # Replacement for reload()
+   def reload_hook(module):
+       name = module.__name__
+       if '.' not in name:
+           return import_module(name, name, None)
+       i = name.rfind('.')
+       pname = name[:i]
+       parent = sys.modules[pname]
+       return import_module(name[i+1:], name, parent)
+
+
+   # Save the original hooks
+   original_import = __builtin__.__import__
+   original_reload = __builtin__.reload
+
+   # Now install our hooks
+   __builtin__.__import__ = import_hook
+   __builtin__.reload = reload_hook
+
+.. index::
+   module: knee
+
+Also see the :mod:`importers` module (which can be found
+in :file:`Demo/imputil/` in the Python source distribution) for additional
+examples.
+

Doc/library/modules.rst

@@ -14,6 +14,7 @@ The full list of modules described in this chapter is:
 .. toctree::
 
    imp.rst
+   imputil.rst
    zipimport.rst
    pkgutil.rst
    modulefinder.rst