Python标准库pkgutil包扩展模块工具

• Z时代
• 2024-01-10
• 分类：综合

源代码: Lib/pkgutil.py

该模块为导入系统提供了工具，尤其是在包支持方面。

class pkgutil.ModuleInfo(module_finder, name, ispkg)¶

一个包含模块信息的简短摘要的命名元组。

3.6 新版功能.

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:

python3 notranslate">

frompkgutilimportextend_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).

class pkgutil.ImpImporter(dirname=None)¶

PEP 302 Finder that wraps Python's "classic" import algorithm.

If dirname is a string, a PEP 302 finder is created that searches that

directory. If dirname is None, a PEP 302 finder is created that

searches the current sys.path, plus any modules that are frozen or

built-in.

Note that ImpImporter does not currently support being used by

placement on sys.meta_path.

3.3 版后已移除: This emulation is no longer needed, as the standard import mechanism

is now fully PEP 302 compliant and available in importlib.

class pkgutil.ImpLoader(fullname, file, filename, etc)¶

Loader that wraps Python's "classic" import algorithm.

3.3 版后已移除: 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.

在 3.3 版更改: Updated to be based directly on importlib rather than relying

on the package internal PEP 302 import emulation.

在 3.4 版更改: 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.

在 3.3 版更改: 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__.

在 3.3 版更改: Updated to be based directly on importlib rather than relying

on the package internal PEP 302 import emulation.

在 3.4 版更改: 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.

在 3.3 版更改: 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 should be either 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.

注解

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.

在 3.3 版更改: 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 should be either 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, ImportErrors

are caught and ignored, while all other exceptions are propagated,

terminating the search.

示例:

python3 notranslate">

# list all modules python can access
walk_packages()
# list all submodules of ctypes
walk_packages(ctypes.__path__,ctypes.__name__+'.')

注解

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.

在 3.3 版更改: Updated to be based directly on importlib rather than relying

on the package internal PEP 302 import emulation.

pkgutil.get_data(package, resource)¶

从包中获取一个资源。

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.