pkgutil
— 包扩展实用程序
¶
源代码： Lib/pkgutil.py
This module provides utilities for the import system, in particular package support.
pkgutil.
ModuleInfo
(
module_finder
,
name
,
ispkg
)
¶
A namedtuple that holds a brief summary of a module’s info.
3.6 版新增。
pkgutil.
extend_path
(
path
,
name
)
¶
Extend the search path for the modules which comprise a package. Intended use is to place the following code in a package’s
__init__.py
:
from pkgutil import extend_path
__path__ = extend_path(__path__, __name__)
This will add to the package’s
__path__
all subdirectories of directories on
sys.path
named after the package. This is useful if one wants to distribute different parts of a single logical package as multiple directories.
It also looks for
*.pkg
files beginning where
*
matches the
name
argument. This feature is similar to
*.pth
files (see the
site
module for more information), except that it doesn’t special-case lines starting with
import
. A
*.pkg
file is trusted at face value: apart from checking for duplicates, all entries found in a
*.pkg
file are added to the path, regardless of whether they exist on the filesystem. (This is a feature.)
If the input path is not a list (as is the case for frozen packages) it is returned unchanged. The input path is not modified; an extended copy is returned. Items are only appended to the copy at the end.
It is assumed that
sys.path
is a sequence. Items of
sys.path
that are not strings referring to existing directories are ignored. Unicode items on
sys.path
that cause errors when used as filenames may cause this function to raise an exception (in line with
os.path.isdir()
behavior).
pkgutil.
ImpImporter
(
dirname=None
)
¶
PEP 302 Finder that wraps Python’s “classic” import algorithm.
若
dirname
is a string, a
PEP 302
finder is created that searches that directory. If
dirname
is
None
，
PEP 302
finder is created that searches the current
sys.path
, plus any modules that are frozen or built-in.
注意，
ImpImporter
does not currently support being used by placement on
sys.meta_path
.
从 3.3 版起弃用：
This emulation is no longer needed, as the standard import mechanism is now fully PEP 302 compliant and available in
importlib
.
pkgutil.
ImpLoader
(
fullname
,
file
,
filename
,
etc
)
¶
Loader that wraps Python’s “classic” import algorithm.
从 3.3 版起弃用：
This emulation is no longer needed, as the standard import mechanism is now fully PEP 302 compliant and available in
importlib
.
pkgutil.
find_loader
(
fullname
)
¶
Retrieve a module loader for the given fullname .
This is a backwards compatibility wrapper around
importlib.util.find_spec()
that converts most failures to
ImportError
and only returns the loader rather than the full
ModuleSpec
.
3.3 版改变：
Updated to be based directly on
importlib
rather than relying on the package internal PEP 302 import emulation.
3.4 版改变： Updated to be based on PEP 451
pkgutil.
get_importer
(
path_item
)
¶
Retrieve a finder for the given path_item .
The returned finder is cached in
sys.path_importer_cache
if it was newly created by a path hook.
The cache (or part of it) can be cleared manually if a rescan of
sys.path_hooks
is necessary.
3.3 版改变：
Updated to be based directly on
importlib
rather than relying on the package internal PEP 302 import emulation.
pkgutil.
get_loader
(
module_or_name
)
¶
Get a loader object for module_or_name .
If the module or package is accessible via the normal import mechanism, a wrapper around the relevant part of that machinery is returned. Returns
None
if the module cannot be found or imported. If the named module is not already imported, its containing package (if any) is imported, in order to establish the package
__path__
.
3.3 版改变：
Updated to be based directly on
importlib
rather than relying on the package internal PEP 302 import emulation.
3.4 版改变： Updated to be based on PEP 451
pkgutil.
iter_importers
(
fullname=''
)
¶
Yield finder objects for the given module name.
If fullname contains a ‘.’, the finders will be for the package containing fullname, otherwise they will be all registered top level finders (i.e. those on both sys.meta_path and sys.path_hooks).
If the named module is in a package, that package is imported as a side effect of invoking this function.
If no module name is specified, all top level finders are produced.
3.3 版改变：
Updated to be based directly on
importlib
rather than relying on the package internal PEP 302 import emulation.
pkgutil.
iter_modules
(
path=None
,
prefix=''
)
¶
Yields
ModuleInfo
for all submodules on
path
, or, if
path
is
None
, all top-level modules on
sys.path
.
path
应该为
None
or a list of paths to look for modules in.
prefix is a string to output on the front of every module name on output.
注意
Only works for a
finder
which defines an
iter_modules()
method. This interface is non-standard, so the module also provides implementations for
importlib.machinery.FileFinder
and
zipimport.zipimporter
.
3.3 版改变：
Updated to be based directly on
importlib
rather than relying on the package internal PEP 302 import emulation.
pkgutil.
walk_packages
(
path=None
,
prefix=''
,
onerror=None
)
¶
Yields
ModuleInfo
for all modules recursively on
path
, or, if
path
is
None
, all accessible modules.
path
应该为
None
or a list of paths to look for modules in.
prefix is a string to output on the front of every module name on output.
Note that this function must import all
packages
(
not
all modules!) on the given
path
, in order to access the
__path__
attribute to find submodules.
onerror
is a function which gets called with one argument (the name of the package which was being imported) if any exception occurs while trying to import a package. If no
onerror
function is supplied,
ImportError
s are caught and ignored, while all other exceptions are propagated, terminating the search.
范例：
# list all modules python can access
walk_packages()
# list all submodules of ctypes
walk_packages(ctypes.__path__, ctypes.__name__ + '.')
注意
Only works for a
finder
which defines an
iter_modules()
method. This interface is non-standard, so the module also provides implementations for
importlib.machinery.FileFinder
and
zipimport.zipimporter
.
3.3 版改变：
Updated to be based directly on
importlib
rather than relying on the package internal PEP 302 import emulation.
pkgutil.
get_data
(
package
,
resource
)
¶
Get a resource from a package.
This is a wrapper for the
loader
get_data
API. The
package
argument should be the name of a package, in standard module format (
foo.bar
). The
resource
argument should be in the form of a relative filename, using
/
as the path separator. The parent directory name
..
is not allowed, and nor is a rooted name (starting with a
/
).
The function returns a binary string that is the contents of the specified resource.
For packages located in the filesystem, which have already been imported, this is the rough equivalent of:
d = os.path.dirname(sys.modules[package].__file__)
data = open(os.path.join(d, resource), 'rb').read()
If the package cannot be located or loaded, or it uses a
loader
which does not support
get_data
, then
None
is returned. In particular, the
loader
for
namespace packages
does not support
get_data
.