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shift demo importers to importers.py (destined for Demo/ ?)

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switch to isinstance() rather than direct type comparisons
removing chaining concept
update ImportManager.install() to take an optional namespace to install
  itself in. this will be useful for setting up rexec environments.
minor comment nits
This commit is contained in:
Greg Stein 2000-02-18 12:03:40 +00:00
parent 18c05f240e
commit d4f1d2074e
1 changed files with 16 additions and 227 deletions
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243
Lib/imputil.py
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@ -10,7 +10,7 @@
# Gordon McMillan.
#
# This module is maintained by Greg and is available at:
# http://www.lyra.org/greg/python/imputil.py
# http://www.lyra.org/greg/python/
#
# Since this isn't in the Python distribution yet, we'll use the CVS ID
# for tracking:
@ -28,20 +28,21 @@
import marshal
_StringType = type('')
_ModuleType = type(sys)
_ModuleType = type(sys) ### doesn't work in JPython...
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
def install(self, namespace=vars(__builtin__)):
"Install this ImportManager into the specified namespace."
if isinstance(namespace, _ModuleType):
namespace = vars(namespace)
### Note that we have no notion of "uninstall" or "chaining"
namespace['__import__'] = self._import_hook
### fix this
#__builtin__.reload = None
#__builtin__.reload = self._reload_hook
#namespace['reload'] = self._reload_hook
def add_suffix(self, suffix, importer):
assert isinstance(importer, SuffixImporter)
@ -94,7 +95,6 @@ def _import_hook(self, fqname, globals=None, locals=None, fromlist=None):
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:
@ -125,7 +125,6 @@ def _import_hook(self, fqname, globals=None, locals=None, fromlist=None):
# 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.
@ -170,7 +169,7 @@ 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:
if isinstance(item, _StringType):
module = self.fs_imp.import_from_dir(item, name)
else:
module = item.import_top(name)
@ -185,7 +184,8 @@ def _reload_hook(self, module):
# 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)
### oops. now what...
pass
# okay. it is using the imputil system, and we must delegate it, but
# we don't know what to do (yet)
@ -269,7 +269,7 @@ def _import_one(self, parent, modname, fqname):
def _process_result(self, (ispkg, code, values), fqname):
# did get_code() return an actual module? (rather than a code object)
is_module = type(code) is _ModuleType
is_module = isinstance(code, _ModuleType)
# use the returned module, or create a new one to exec code into
if is_module:
@ -379,15 +379,12 @@ def get_code(self, parent, modname, fqname):
# Some handy stuff for the Importers
#
# byte-compiled file suffic character
# byte-compiled file suffix character
_suffix_char = __debug__ and 'c' or 'o'
# byte-compiled file suffix
_suffix = '.py' + _suffix_char
# the C_EXTENSION suffixes
_c_suffixes = filter(lambda x: x[2] == imp.C_EXTENSION, imp.get_suffixes())
def _compile(pathname, timestamp):
"""Compile (and cache) a Python source file.
@ -483,202 +480,6 @@ def _timestamp(pathname):
return None
return long(s[8])
def _fs_import(dir, modname, fqname):
"Fetch a module from the filesystem."
pathname = _os_path_join(dir, modname)
if _os_path_isdir(pathname):
values = { '__pkgdir__' : pathname, '__path__' : [ pathname ] }
ispkg = 1
pathname = _os_path_join(pathname, '__init__')
else:
values = { }
ispkg = 0
# look for dynload modules
for desc in _c_suffixes:
file = pathname + desc[0]
try:
fp = open(file, desc[1])
except IOError:
pass
else:
module = imp.load_module(fqname, fp, file, desc)
values['__file__'] = file
return 0, module, values
t_py = _timestamp(pathname + '.py')
t_pyc = _timestamp(pathname + _suffix)
if t_py is None and t_pyc is None:
return None
code = None
if t_py is None or (t_pyc is not None and t_pyc >= t_py):
file = pathname + _suffix
f = open(file, 'rb')
if f.read(4) == imp.get_magic():
t = struct.unpack('<I', f.read(4))[0]
if t == t_py:
code = marshal.load(f)
f.close()
if code is None:
file = pathname + '.py'
code = _compile(file, t_py)
values['__file__'] = file
return ispkg, code, values
######################################################################
#
# Simple function-based importer
#
class FuncImporter(Importer):
"Importer subclass to use a supplied function rather than method overrides."
def __init__(self, func):
self.func = func
def get_code(self, parent, modname, fqname):
return self.func(parent, modname, fqname)
def install_with(func):
FuncImporter(func).install()
######################################################################
#
# Base class for archive-based importing
#
class PackageArchiveImporter(Importer):
"""Importer subclass to import from (file) archives.
This Importer handles imports of the style <archive>.<subfile>, where
<archive> can be located using a subclass-specific mechanism and the
<subfile> is found in the archive using a subclass-specific mechanism.
This class defines two hooks for subclasses: one to locate an archive
(and possibly return some context for future subfile lookups), and one
to locate subfiles.
"""
def get_code(self, parent, modname, fqname):
if parent:
# the Importer._finish_import logic ensures that we handle imports
# under the top level module (package / archive).
assert parent.__importer__ == self
# if a parent "package" is provided, then we are importing a sub-file
# from the archive.
result = self.get_subfile(parent.__archive__, modname)
if result is None:
return None
if type(result) == type(()):
return (0,) + result
return 0, result
# no parent was provided, so the archive should exist somewhere on the
# default "path".
archive = self.get_archive(modname)
if archive is None:
return None
return 1, "", {'__archive__':archive}
def get_archive(self, modname):
"""Get an archive of modules.
This method should locate an archive and return a value which can be
used by get_subfile to load modules from it. The value may be a simple
pathname, an open file, or a complex object that caches information
for future imports.
Return None if the archive was not found.
"""
raise RuntimeError, "get_archive not implemented"
def get_subfile(self, archive, modname):
"""Get code from a subfile in the specified archive.
Given the specified archive (as returned by get_archive()), locate
and return a code object for the specified module name.
A 2-tuple may be returned, consisting of a code object and a dict
of name/values to place into the target module.
Return None if the subfile was not found.
"""
raise RuntimeError, "get_subfile not implemented"
class PackageArchive(PackageArchiveImporter):
"PackageArchiveImporter subclass that refers to a specific archive."
def __init__(self, modname, archive_pathname):
self.__modname = modname
self.__path = archive_pathname
def get_archive(self, modname):
if modname == self.__modname:
return self.__path
return None
# get_subfile is passed the full pathname of the archive
######################################################################
#
# Emulate the standard directory-based import mechanism
#
class DirectoryImporter(Importer):
"Importer subclass to emulate the standard importer."
def __init__(self, dir):
self.dir = dir
def get_code(self, parent, modname, fqname):
if parent:
dir = parent.__pkgdir__
else:
dir = self.dir
# defer the loading of OS-related facilities
if not _os_stat:
_os_bootstrap()
# Return the module (and other info) if found in the specified
# directory. Otherwise, return None.
return _fs_import(dir, modname, fqname)
def __repr__(self):
return '<%s.%s for "%s" at 0x%x>' % (self.__class__.__module__,
self.__class__.__name__,
self.dir,
id(self))
######################################################################
#
# Emulate the standard path-style import mechanism
#
class PathImporter(Importer):
def __init__(self, path=sys.path):
self.path = path
# 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()
def get_code(self, parent, modname, fqname):
if parent:
# we are looking for a module inside of a specific package
return _fs_import(parent.__pkgdir__, modname, fqname)
# scan sys.path, looking for the requested module
for dir in self.path:
result = _fs_import(dir, modname, fqname)
if result:
return result
# not found
return None
######################################################################
#
@ -792,18 +593,6 @@ def import_file(self, filename, finfo, fqname):
######################################################################
def _test_dir():
"Debug/test function to create DirectoryImporters from sys.path."
path = sys.path[:]
path.reverse()
for d in path:
DirectoryImporter(d).install()
def _test_revamp():
"Debug/test function for the revamped import system."
PathImporter().install()
BuiltinImporter().install()
def _print_importers():
items = sys.modules.items()
items.sort()