Edit File: imputil.txt
:mod:`imputil` --- Import utilities ===================================================== .. module:: imputil :synopsis: Manage and augment the import process. :deprecated: .. deprecated:: 2.6 The :mod:`imputil` module has been removed in Python 3. .. index:: statement: import This module provides a very handy and useful mechanism for custom :keyword:`import` hooks. Compared to the older :mod:`ihooks` module, :mod:`imputil` 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 built-in and frozen modules. This is a sub-class of the :class:`Importer` class. .. 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 clunkier 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.