From f23aa1ee9facd990c8cf102ed69d56e2a688730d Mon Sep 17 00:00:00 2001 From: Greg Stein Date: Mon, 3 Jan 2000 02:38:29 +0000 Subject: redesign/rebuild around the ImportManager concept. --- Lib/imputil.py | 440 ++++++++++++++++++++++++++++++++++++++------------------- 1 file changed, 291 insertions(+), 149 deletions(-) diff --git a/Lib/imputil.py b/Lib/imputil.py index 6d70938..3417ea6 100644 --- a/Lib/imputil.py +++ b/Lib/imputil.py @@ -27,105 +27,105 @@ import __builtin__ import struct import marshal -class Importer: - "Base class for replacing standard import functions." +_StringType = type('') +_ModuleType = type(sys) + +class ImportManager: + "Manage the import process." def install(self): + ### warning: Python 1.6 will have a different hook mechanism; this + ### code will need to change. self.__chain_import = __builtin__.__import__ self.__chain_reload = __builtin__.reload __builtin__.__import__ = self._import_hook - __builtin__.reload = self._reload_hook + ### fix this + #__builtin__.reload = None + #__builtin__.reload = self._reload_hook + + def add_suffix(self, suffix, importer): + assert isinstance(importer, SuffixImporter) + self.suffixes.append((suffix, importer)) ###################################################################### # # PRIVATE METHODS # - def _import_hook(self, name, globals=None, locals=None, fromlist=None): - """Python calls this hook to locate and import a module. + def __init__(self): + # we're definitely going to be importing something in the future, + # so let's just load the OS-related facilities. + if not _os_stat: + _os_bootstrap() - This method attempts to load the (dotted) module name. If it cannot - find it, then it delegates the import to the next import hook in the - chain (where "next" is defined as the import hook that was in place - at the time this Importer instance was installed). - """ + # Initialize the set of suffixes that we recognize and import. + # The default will import dynamic-load modules first, followed by + # .py files (or a .py file's cached bytecode) + self.suffixes = [ ] + for desc in imp.get_suffixes(): + if desc[2] == imp.C_EXTENSION: + self.suffixes.append((desc[0], DynLoadSuffixImporter(desc))) + self.suffixes.append(('.py', PySuffixImporter())) + + # This is the importer that we use for grabbing stuff from the + # filesystem. It defines one more method (import_from_dir) for our use. + self.fs_imp = _FilesystemImporter(self.suffixes) - ### insert a fast-path check for whether the module is already - ### loaded? use a variant of _determine_import_context() which - ### returns a context regardless of Importer used. generate an - ### fqname and look in sys.modules for it. + def _import_hook(self, fqname, globals=None, locals=None, fromlist=None): + """Python calls this hook to locate and import a module.""" - ### note that given module a.b which imports c, if c is already - ### loaded, python still wants to look for a.c + parts = strop.split(fqname, '.') # determine the context of this import parent = self._determine_import_context(globals) - # import the module within the context, or from the default context - top, tail = self._import_top_module(parent, name) - if top is None: - # the module was not found; delegate to the next import hook - return self.__chain_import(name, globals, locals, fromlist) - - # the top module may be under the control of a different importer. - # if so, then defer to that importer for completion of the import. - # note it may be self, or is undefined so we (self) may as well - # finish the import. - importer = top.__dict__.get('__importer__', self) - return importer._finish_import(top, tail, fromlist) - - def _finish_import(self, top, tail, fromlist): - # if "a.b.c" was provided, then load the ".b.c" portion down from - # below the top-level module. - bottom = self._load_tail(top, tail) - - # if the form is "import a.b.c", then return "a" - if not fromlist: - # no fromlist: return the top of the import tree - return top - - # the top module was imported by self, or it was not imported through - # the Importer mechanism and self is simply handling the import of - # the sub-modules and fromlist. - # - # this means that the bottom module was also imported by self, or we - # are handling things in the absence of a prior Importer - # - # ### why the heck are we handling it? what is the example scenario - # ### where this happens? note that we can't determine is_package() - # ### for non-Importer modules. - # - # since we imported/handled the bottom module, this means that we can - # also handle its fromlist (and reliably determine is_package()). - - # if the bottom node is a package, then (potentially) import some modules. - # - # note: if it is not a package, then "fromlist" refers to names in - # the bottom module rather than modules. - # note: for a mix of names and modules in the fromlist, we will - # import all modules and insert those into the namespace of - # the package module. Python will pick up all fromlist names - # from the bottom (package) module; some will be modules that - # we imported and stored in the namespace, others are expected - # to be present already. - if self._is_package(bottom.__dict__): - self._import_fromlist(bottom, fromlist) - - # if the form is "from a.b import c, d" then return "b" - return bottom - - def _reload_hook(self, module): - "Python calls this hook to reload a module." + # if there is a parent, then its importer should manage this import + if parent: + module = parent.__importer__._do_import(parent, parts, fromlist) + if module: + return module - # reloading of a module may or may not be possible (depending on the - # importer), but at least we can validate that it's ours to reload - importer = module.__dict__.get('__importer__', None) - if importer is not self: - return self.__chain_reload(module) + # has the top module already been imported? + try: + top_module = sys.modules[parts[0]] + except KeyError: - # okay. it is ours, but we don't know what to do (yet) - ### we should blast the module dict and do another get_code(). need to - ### flesh this out and add proper docco... - raise SystemError, "reload not yet implemented" + # look for the topmost module + top_module = self._import_top_module(parts[0]) + if not top_module: + # the topmost module wasn't found at all. + raise ImportError, 'No module named ' + fqname + return self.__chain_import(name, globals, locals, fromlist) + + # fast-path simple imports + if len(parts) == 1: + if not fromlist: + return top_module + + if not top_module.__dict__.get('__ispkg__'): + # __ispkg__ isn't defined (the module was not imported by us), or + # it is zero. + # + # In the former case, there is no way that we could import + # sub-modules that occur in the fromlist (but we can't raise an + # error because it may just be names) because we don't know how + # to deal with packages that were imported by other systems. + # + # In the latter case (__ispkg__ == 0), there can't be any sub- + # modules present, so we can just return. + # + # In both cases, since len(parts) == 1, the top_module is also + # the "bottom" which is the defined return when a fromlist exists. + return top_module + + importer = top_module.__dict__.get('__importer__') + if importer: + return importer._finish_import(top_module, parts[1:], fromlist) + + # If the importer does not exist, then we have to bail. A missing importer + # means that something else imported the module, and we have no knowledge + # of how to get sub-modules out of the thing. + raise ImportError, 'No module named ' + fqname + return self.__chain_import(name, globals, locals, fromlist) def _determine_import_context(self, globals): """Returns the context in which a module should be imported. @@ -136,19 +136,19 @@ class Importer: "top-level" module. """ - if not globals or \ - globals.get('__importer__', None) is not self: - # globals does not refer to one of our modules or packages. - # That implies there is no relative import context, and it - # should just pick it off the standard path. + if not globals or not globals.get('__importer__'): + # globals does not refer to one of our modules or packages. That + # implies there is no relative import context (as far as we are + # concerned), and it should just pick it off the standard path. return None # The globals refer to a module or package of ours. It will define # the context of the new import. Get the module/package fqname. parent_fqname = globals['__name__'] - # for a package, return itself (imports refer to pkg contents) - if self._is_package(globals): + # if a package is performing the import, then return itself (imports + # refer to pkg contents) + if globals['__ispkg__']: parent = sys.modules[parent_fqname] assert globals is parent.__dict__ return parent @@ -159,46 +159,88 @@ class Importer: if i == -1: return None - # for a module in a package, return the package (imports refer to siblings) + # if a module in a package is performing the import, then return the + # package (imports refer to siblings) parent_fqname = parent_fqname[:i] parent = sys.modules[parent_fqname] assert parent.__name__ == parent_fqname return parent - def _import_top_module(self, parent, name): - """Locate the top of the import tree (relative or absolute). + def _import_top_module(self, name): + # scan sys.path looking for a location in the filesystem that contains + # the module, or an Importer object that can import the module. + for item in sys.path: + if type(item) == _StringType: + module = self.fs_imp.import_from_dir(item, name) + else: + module = item.import_top(name) + if module: + return module + return None + + def _reload_hook(self, module): + "Python calls this hook to reload a module." - parent defines the context in which the import should occur. See - _determine_import_context() for details. + # reloading of a module may or may not be possible (depending on the + # importer), but at least we can validate that it's ours to reload + importer = module.__dict__.get('__importer__') + if not importer: + return self.__chain_reload(module) - Returns a tuple (module, tail). module is the loaded (top-level) module, - or None if the module is not found. tail is the remaining portion of - the dotted name. - """ - i = strop.find(name, '.') - if i == -1: - head = name - tail = "" - else: - head = name[:i] - tail = name[i+1:] - if parent: - fqname = "%s.%s" % (parent.__name__, head) - else: - fqname = head - module = self._import_one(parent, head, fqname) - if module: - # the module was relative, or no context existed (the module was - # simply found on the path). - return module, tail - if parent: - # we tried relative, now try an absolute import (from the path) - module = self._import_one(None, head, head) - if module: - return module, tail + # okay. it is using the imputil system, and we must delegate it, but + # we don't know what to do (yet) + ### we should blast the module dict and do another get_code(). need to + ### flesh this out and add proper docco... + raise SystemError, "reload not yet implemented" - # the module wasn't found - return None, None + +class Importer: + "Base class for replacing standard import functions." + + def install(self): + sys.path.insert(0, self) + + def import_top(self, name): + "Import a top-level module." + return self._import_one(None, name, name) + + ###################################################################### + # + # PRIVATE METHODS + # + def _finish_import(self, top, parts, fromlist): + # if "a.b.c" was provided, then load the ".b.c" portion down from + # below the top-level module. + bottom = self._load_tail(top, parts) + + # if the form is "import a.b.c", then return "a" + if not fromlist: + # no fromlist: return the top of the import tree + return top + + # the top module was imported by self. + # + # this means that the bottom module was also imported by self (just + # now, or in the past and we fetched it from sys.modules). + # + # since we imported/handled the bottom module, this means that we can + # also handle its fromlist (and reliably use __ispkg__). + + # if the bottom node is a package, then (potentially) import some modules. + # + # note: if it is not a package, then "fromlist" refers to names in + # the bottom module rather than modules. + # note: for a mix of names and modules in the fromlist, we will + # import all modules and insert those into the namespace of + # the package module. Python will pick up all fromlist names + # from the bottom (package) module; some will be modules that + # we imported and stored in the namespace, others are expected + # to be present already. + if bottom.__ispkg__: + self._import_fromlist(bottom, fromlist) + + # if the form is "from a.b import c, d" then return "b" + return bottom def _import_one(self, parent, modname, fqname): "Import a single module." @@ -214,46 +256,53 @@ class Importer: if result is None: return None + ### backwards-compat + if len(result) == 2: + result = result + ({},) + + module = self._process_result(result, fqname) + + # insert the module into its parent + if parent: + setattr(parent, modname, module) + return module + + def _process_result(self, (ispkg, code, values), fqname): # did get_code() return an actual module? (rather than a code object) - is_module = type(result[1]) is type(sys) + is_module = type(code) is _ModuleType # use the returned module, or create a new one to exec code into if is_module: - module = result[1] + module = code else: module = imp.new_module(fqname) ### record packages a bit differently?? module.__importer__ = self - module.__ispkg__ = result[0] + module.__ispkg__ = ispkg - # if present, the third item is a set of values to insert into the module - if len(result) > 2: - module.__dict__.update(result[2]) + # insert additional values into the module (before executing the code) + module.__dict__.update(values) # the module is almost ready... make it visible sys.modules[fqname] = module # execute the code within the module's namespace if not is_module: - exec result[1] in module.__dict__ + exec code in module.__dict__ - # insert the module into its parent - if parent: - setattr(parent, modname, module) return module - def _load_tail(self, m, tail): + def _load_tail(self, m, parts): """Import the rest of the modules, down from the top-level module. Returns the last module in the dotted list of modules. """ - if tail: - for part in strop.splitfields(tail, '.'): - fqname = "%s.%s" % (m.__name__, part) - m = self._import_one(m, part, fqname) - if not m: - raise ImportError, "No module named " + fqname + for part in parts: + fqname = "%s.%s" % (m.__name__, part) + m = self._import_one(m, part, fqname) + if not m: + raise ImportError, "No module named " + fqname return m def _import_fromlist(self, package, fromlist): @@ -273,17 +322,20 @@ class Importer: if not submod: raise ImportError, "cannot import name " + subname - def _is_package(self, module_dict): - """Determine if a given module (dictionary) specifies a package. - - The package status is in the module-level name __ispkg__. The module - must also have been imported by self, so that we can reliably apply - semantic meaning to __ispkg__. + def _do_import(self, parent, parts, fromlist): + """Attempt to import the module relative to parent. - ### weaken the test to issubclass(Importer)? + This method is used when the import context specifies that + imported the parent module. """ - return module_dict.get('__importer__', None) is self and \ - module_dict['__ispkg__'] + top_name = parts[0] + top_fqname = parent.__name__ + '.' + top_name + top_module = self._import_one(parent, top_name, top_fqname) + if not top_module: + # this importer and parent could not find the module (relatively) + return None + + return self._finish_import(top_module, parts[1:], fromlist) ###################################################################### # @@ -301,7 +353,7 @@ class Importer: 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, a 2-tuple, or a 3-tuple. + This method should return None, or a 3-tuple. * If the module was not found, then None should be returned. @@ -312,9 +364,9 @@ class Importer: executed within the new module's namespace). This item can also be a fully-loaded module object (e.g. loaded from a shared lib). - * If present, the third item is a dictionary of name/value pairs that - will be inserted into new module before the code object is executed. - This provided in case the module's code expects certain values (such + * 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. @@ -653,6 +705,92 @@ class BuiltinImporter(Importer): ###################################################################### +# +# Internal importer used for importing from the filesystem +# +class _FilesystemImporter(Importer): + def __init__(self, suffixes): + # this list is shared with the ImportManager. + self.suffixes = suffixes + + def import_from_dir(self, dir, fqname): + result = self._import_pathname(_os_path_join(dir, fqname), fqname) + if result: + return self._process_result(result, fqname) + return None + + def get_code(self, parent, modname, fqname): + # This importer is never used with an empty parent. Its existence is + # private to the ImportManager. The ImportManager uses the + # import_from_dir() method to import top-level modules/packages. + # This method is only used when we look for a module within a package. + assert parent + + return self._import_pathname(_os_path_join(parent.__pkgdir__, modname), + fqname) + + def _import_pathname(self, pathname, fqname): + if _os_path_isdir(pathname): + result = self._import_pathname(_os_path_join(pathname, '__init__'), + fqname) + if result: + values = result[2] + values['__pkgdir__'] = pathname + values['__path__'] = [ pathname ] + return 1, result[1], values + return None + + for suffix, importer in self.suffixes: + filename = pathname + suffix + try: + finfo = _os_stat(filename) + except OSError: + pass + else: + return importer.import_file(filename, finfo, fqname) + return None + +###################################################################### +# +# SUFFIX-BASED IMPORTERS +# + +class SuffixImporter: + def import_file(self, filename, finfo, fqname): + raise RuntimeError + +class PySuffixImporter(SuffixImporter): + def import_file(self, filename, finfo, fqname): + file = filename[:-3] + _suffix + t_py = long(finfo[8]) + t_pyc = _timestamp(file) + + code = None + if t_pyc is not None and t_pyc >= t_py: + f = open(file, 'rb') + if f.read(4) == imp.get_magic(): + t = struct.unpack('