importlib
– 实现为
import
¶
3.1 版新增。
目地对于
importlib
package is two-fold. One is to provide the implementation of the
import
statement (and thus, by extension, the
__import__()
function) in Python source code. This provides an implementation of
import
which is portable to any Python interpreter. This also provides an implementation which is easier to comprehend than one implemented in a programming language other than Python.
Two, the components to implement
import
are exposed in this package, making it easier for users to create their own custom objects (known generically as an
importer
) to participate in the import process.
另请参阅
import
语句。
None
in
sys.modules
).
__import__()
function
import
语句是用于此函数的句法糖。
importlib.
__import__
(
name
,
globals=None
,
locals=None
,
fromlist=()
,
level=0
)
¶
实现内置
__import__()
函数。
importlib.
import_module
(
name
,
package=None
)
¶
导入模块。
name
自变量按绝对 (或相对) 术语方式指定要导入什么模块 (如
pkg.mod
or
..mod
)。若名称以相对术语方式指定，那么
package
自变量必须被设为充当解析包名的锚点包的名称 (如
import_module('..mod', 'pkg.subpkg')
将导入
pkg.mod
).
The
import_module()
函数充当简化包裹器围绕
importlib.__import__()
。这意味着函数的所有语义均派生自
importlib.__import__()
, including requiring the package from which an import is occurring to have been previously imported (i.e.,
package
must already be imported). The most important difference is that
import_module()
返回指定包或模块 (如
pkg.mod
)，而
__import__()
返回顶层包或模块 (如
pkg
).
3.3 版改变： 自动导入父级包。
importlib.
find_loader
(
name
,
path=None
)
¶
查找模块加载器，可选指定
path
。若模块在
sys.modules
，那么
sys.modules[name].__loader__
被返回 (除非加载器将为
None
或未设置，在这种情况下
ValueError
被引发)。否则，搜索使用
sys.meta_path
完成。
None
被返回，若找不到加载器。
A dotted name does not have its parent’s implicitly imported as that requires loading them and that may not be desired. To properly import a submodule you will need to import all parent packages of the submodule and use the correct argument to path .
3.3 版新增。
3.4 版改变：
若
__loader__
未设置，引发
ValueError
，就像当把属性设为
None
.
从 3.4 版起弃用：
使用
importlib.util.find_spec()
代替。
importlib.
invalidate_caches
(
)
¶
使内部缓存无效的查找器存储在
sys.meta_path
。若查找器有实现
invalidate_caches()
那么调用它将履行无效操作。应调用此函数，若运行程序时有创建/安装任何模块，以保证所有查找器都注意到新模块的存在。
3.3 版新增。
importlib.
reload
(
module
)
¶
重新加载先前导入的
module
。自变量是模块对象，所以之前必须成功导入它。这很有用，若有使用外部编辑器编辑模块源文件，且想要不离开 Python 解释器试用新版本。返回值是模块对象 (可能不同，若重新导入导致不同对象被放置在
sys.modules
).
当
reload()
被执行：
init
function of extension modules is not called a second
time.
有很多其它告诫：
When a module is reloaded, its dictionary (containing the module’s global variables) is retained. Redefinitions of names will override the old definitions, so this is generally not a problem. If the new version of a module does not define a name that was defined by the old version, the old definition remains. This feature can be used to the module’s advantage if it maintains a global table or cache of objects — with a
try
statement it can test for the table’s presence and skip its initialization if desired:
try: cache except NameError: cache = {}
It is generally not very useful to reload built-in or dynamically loaded modules. Reloading
sys
,
__main__
,
builtins
and other key modules is not recommended. In many cases extension modules are not designed to be initialized more than once, and may fail in arbitrary ways when reloaded.
If a module imports objects from another module using
from
...
import
..., calling
reload()
for the other module does not redefine the objects imported from it — one way around this is to re-execute the
from
statement, another is to use
import
and qualified names (
module.name
) 代替。
If a module instantiates instances of a class, reloading the module that defines the class does not affect the method definitions of the instances — they continue to use the old class definition. The same is true for derived classes.
3.4 版新增。
importlib.abc
– 导入相关 ABC (抽象基类)
¶
The
importlib.abc
module contains all of the core abstract base classes used by
import
. Some subclasses of the core abstract base classes are also provided to help in implementing the core ABCs.
ABC hierarchy:
object +-- Finder (deprecated) | +-- MetaPathFinder | +-- PathEntryFinder +-- Loader +-- ResourceLoader --------+ +-- InspectLoader | +-- ExecutionLoader --+ +-- FileLoader +-- SourceLoader
importlib.abc.
Finder
¶
An abstract base class representing a finder .
从 3.3 版起弃用：
使用
MetaPathFinder
or
PathEntryFinder
代替。
find_module
(
fullname
,
path=None
)
¶
An abstact method for finding a
loader
for the specified module. Originally specified in
PEP 302
, this method was meant for use in
sys.meta_path
and in the path-based import subsystem.
3.4 版改变：
返回
None
当调用而不是引发
NotImplementedError
.
importlib.abc.
MetaPathFinder
¶
An abstract base class representing a
元路径查找器
. For compatibility, this is a subclass of
Finder
.
3.3 版新增。
find_spec
(
fullname
,
path
,
target=None
)
¶
An abstract method for finding a
spec
for the specified module. If this is a top-level import,
path
将是
None
. Otherwise, this is a search for a subpackage or module and
path
will be the value of
__path__
from the parent package. If a spec cannot be found,
None
is returned. When passed in,
target
is a module object that the finder may use to make a more educated about what spec to return.
3.4 版新增。
find_module
(
fullname
,
path
)
¶
传统方法用于查找
loader
for the specified module. If this is a top-level import,
path
将是
None
. Otherwise, this is a search for a subpackage or module and
path
will be the value of
__path__
from the parent package. If a loader cannot be found,
None
被返回。
若
find_spec()
is defined, backwards-compatible functionality is provided.
3.4 版改变：
返回
None
当调用而不是引发
NotImplementedError
。可以使用
find_spec()
来提供功能。
从 3.4 版起弃用：
使用
find_spec()
代替。
invalidate_caches
(
)
¶
An optional method which, when called, should invalidate any internal cache used by the finder. Used by
importlib.invalidate_caches()
when invalidating the caches of all finders on
sys.meta_path
.
3.4 版改变：
返回
None
当调用而不是
NotImplemented
.
importlib.abc.
PathEntryFinder
¶
An abstract base class representing a
路径条目查找器
. Though it bears some similarities to
MetaPathFinder
,
PathEntryFinder
is meant for use only within the path-based import subsystem provided by
PathFinder
. This ABC is a subclass of
Finder
for compatibility reasons only.
3.3 版新增。
find_spec
(
fullname
,
target=None
)
¶
An abstract method for finding a
spec
for the specified module. The finder will search for the module only within the
路径条目
to which it is assigned. If a spec cannot be found,
None
is returned. When passed in,
target
is a module object that the finder may use to make a more educated about what spec to return.
3.4 版新增。
find_loader
(
fullname
)
¶
传统方法用于查找
loader
for the specified module. Returns a 2-tuple of
(loader, portion)
where
portion
is a sequence of file system locations contributing to part of a namespace package. The loader may be
None
while specifying
portion
to signify the contribution of the file system locations to a namespace package. An empty list can be used for
portion
to signify the loader is not part of a namespace package. If
loader
is
None
and
portion
is the empty list then no loader or location for a namespace package were found (i.e. failure to find anything for the module).
若
find_spec()
is defined then backwards-compatible functionality is provided.
3.4 版改变：
返回
(None, [])
而不是引发
NotImplementedError
. Uses
find_spec()
when available to provide functionality.
从 3.4 版起弃用：
使用
find_spec()
代替。
find_module
(
fullname
)
¶
A concrete implementation of
Finder.find_module()
相当于
self.find_loader(fullname)[0]
.
从 3.4 版起弃用：
使用
find_spec()
代替。
invalidate_caches
(
)
¶
An optional method which, when called, should invalidate any internal cache used by the finder. Used by
PathFinder.invalidate_caches()
when invalidating the caches of all cached finders.
importlib.abc.
Loader
¶
An abstract base class for a loader 。见 PEP 302 for the exact definition for a loader.
create_module
(
spec
)
¶
An optional method that returns the module object to use when importing a module. create_module() may also return
None
, indicating that the default module creation should take place instead.
3.4 版新增。
exec_module
(
module
)
¶
An abstract method that executes the module in its own namespace when a module is imported or reloaded. The module should already be initialized when exec_module() is called.
3.4 版新增。
load_module
(
fullname
)
¶
A legacy method for loading a module. If the module cannot be loaded,
ImportError
is raised, otherwise the loaded module is returned.
If the requested module already exists in
sys.modules
, that module should be used and reloaded. Otherwise the loader should create a new module and insert it into
sys.modules
before any loading begins, to prevent recursion from the import. If the loader inserted a module and the load fails, it must be removed by the loader from
sys.modules
; modules already in
sys.modules
before the loader began execution should be left alone (see
importlib.util.module_for_loader()
).
The loader should set several attributes on the module. (Note that some of these attributes can change when a module is reloaded):
__name__
The name of the module.
__file__
The path to where the module data is stored (not set for built-in modules).
__cached__
The path to where a compiled version of the module is/should be stored (not set when the attribute would be inappropriate).
__path__
A list of strings specifying the search path within a package. This attribute is not set on modules.
__package__
The parent package for the module/package. If the module is top-level then it has a value of the empty string. The
importlib.util.module_for_loader()
decorator can handle the details for
__package__
.
__loader__
The loader used to load the module. The
importlib.util.module_for_loader()
decorator can handle the details for
__package__
.
当
exec_module()
is available then backwards-compatible functionality is provided.
3.4 版改变：
引发
ImportError
当调用而不是
NotImplementedError
. Functionality provided when
exec_module()
可用。
从 3.4 版起弃用：
The recommended API for loading a module is
exec_module()
(and optionally
create_module()
). Loaders should implement it instead of load_module(). The import machinery takes care of all the other responsibilities of load_module() when exec_module() is implemented.
module_repr
(
module
)
¶
A legacy method which when implemented calculates and returns the given module’s repr, as a string. The module type’s default repr() will use the result of this method as appropriate.
3.3 版新增。
3.4 版改变： Made optional instead of an abstractmethod.
从 3.4 版起弃用： The import machinery now takes care of this automatically.
importlib.abc.
ResourceLoader
¶
An abstract base class for a loader which implements the optional PEP 302 protocol for loading arbitrary resources from the storage back-end.
get_data
(
path
)
¶
An abstract method to return the bytes for the data located at
path
. Loaders that have a file-like storage back-end that allows storing arbitrary data can implement this abstract method to give direct access to the data stored.
OSError
is to be raised if the
path
cannot be found. The
path
is expected to be constructed using a module’s
__file__
attribute or an item from a package’s
__path__
.
3.4 版改变：
引发
OSError
而不是
NotImplementedError
.
importlib.abc.
InspectLoader
¶
An abstract base class for a loader which implements the optional PEP 302 protocol for loaders that inspect modules.
get_code
(
fullname
)
¶
Return the code object for a module, or
None
if the module does not have a code object (as would be the case, for example, for a built-in module). Raise an
ImportError
if loader cannot find the requested module.
注意
While the method has a default implementation, it is suggested that it be overridden if possible for performance.
3.4 版改变： No longer abstract and a concrete implementation is provided.
get_source
(
fullname
)
¶
An abstract method to return the source of a module. It is returned as a text string using
通用换行符
, translating all recognized line separators into
'\n'
characters. Returns
None
if no source is available (e.g. a built-in module). Raises
ImportError
if the loader cannot find the module specified.
3.4 版改变：
引发
ImportError
而不是
NotImplementedError
.
is_package
(
fullname
)
¶
An abstract method to return a true value if the module is a package, a false value otherwise.
ImportError
is raised if the
loader
cannot find the module.
3.4 版改变：
引发
ImportError
而不是
NotImplementedError
.
source_to_code
(
data
,
path='<string>'
)
¶
Create a code object from Python source.
The
data
argument can be whatever the
compile()
function supports (i.e. string or bytes). The
path
argument should be the “path” to where the source code originated from, which can be an abstract concept (e.g. location in a zip file).
3.4 版新增。
exec_module
(
module
)
¶
Implementation of
Loader.exec_module()
.
3.4 版新增。
load_module
(
fullname
)
¶
Implementation of
Loader.load_module()
.
从 3.4 版起弃用：
使用
exec_module()
代替。
importlib.abc.
ExecutionLoader
¶
An abstract base class which inherits from
InspectLoader
that, when implemented, helps a module to be executed as a script. The ABC represents an optional
PEP 302
协议。
get_filename
(
fullname
)
¶
An abstract method that is to return the value of
__file__
for the specified module. If no path is available,
ImportError
被引发。
If source code is available, then the method should return the path to the source file, regardless of whether a bytecode was used to load the module.
3.4 版改变：
引发
ImportError
而不是
NotImplementedError
.
importlib.abc.
FileLoader
(
fullname
,
path
)
¶
An abstract base class which inherits from
ResourceLoader
and
ExecutionLoader
, providing concrete implementations of
ResourceLoader.get_data()
and
ExecutionLoader.get_filename()
.
The fullname argument is a fully resolved name of the module the loader is to handle. The path argument is the path to the file for the module.
3.3 版新增。
名称
¶
The name of the module the loader can handle.
path
¶
模块文件的路径。
load_module
(
fullname
)
¶
Calls super’s
load_module()
.
从 3.4 版起弃用：
使用
Loader.exec_module()
代替。
get_data
(
path
)
¶
读取 path as a binary file and returns the bytes from it.
importlib.abc.
SourceLoader
¶
An abstract base class for implementing source (and optionally bytecode) file loading. The class inherits from both
ResourceLoader
and
ExecutionLoader
, requiring the implementation of:
ExecutionLoader.get_filename()
Should only return the path to the source file; sourceless loading is not supported.
The abstract methods defined by this class are to add optional bytecode file support. Not implementing these optional methods (or causing them to raise
NotImplementedError
) causes the loader to only work with source code. Implementing the methods allows the loader to work with source
and
bytecode files; it does not allow for
sourceless
loading where only bytecode is provided. Bytecode files are an optimization to speed up loading by removing the parsing step of Python’s compiler, and so no bytecode-specific API is exposed.
path_stats
(
path
)
¶
Optional abstract method which returns a
dict
containing metadata about the specifed path. Supported dictionary keys are:
'mtime'
(mandatory): an integer or floating-point number
representing the modification time of the source code;
'size'
(optional): the size in bytes of the source code.
Any other keys in the dictionary are ignored, to allow for future extensions. If the path cannot be handled,
OSError
被引发。
3.3 版新增。
3.4 版改变：
引发
OSError
而不是
NotImplementedError
.
path_mtime
(
path
)
¶
Optional abstract method which returns the modification time for the specified path.
从 3.3 版起弃用：
This method is deprecated in favour of
path_stats()
. You don’t have to implement it, but it is still available for compatibility purposes. Raise
OSError
if the path cannot be handled.
3.4 版改变：
引发
OSError
而不是
NotImplementedError
.
set_data
(
path
,
data
)
¶
Optional abstract method which writes the specified bytes to a file path. Any intermediate directories which do not exist are to be created automatically.
When writing to the path fails because the path is read-only (
errno.EACCES
/
PermissionError
)，不传播异常。
3.4 版改变：
不再引发
NotImplementedError
当调用时。
get_code
(
fullname
)
¶
具体实现的
InspectLoader.get_code()
.
exec_module
(
module
)
¶
Loader.exec_module()
.
3.4 版新增。
load_module
(
fullname
)
¶
具体实现的
Loader.load_module()
.
从 3.4 版起弃用：
使用
exec_module()
代替。
get_source
(
fullname
)
¶
具体实现的
InspectLoader.get_source()
.
is_package
(
fullname
)
¶
具体实现的
InspectLoader.is_package()
. A module is determined to be a package if its file path (as provided by
ExecutionLoader.get_filename()
) is a file named
__init__
when the file extension is removed
and
the module name itself does not end in
__init__
.
importlib.machinery
– 导入器和路径挂钩
¶
此模块包含的各种对象帮助
import
查找和加载模块。
importlib.machinery.
SOURCE_SUFFIXES
¶
A list of strings representing the recognized file suffixes for source modules.
3.3 版新增。
importlib.machinery.
DEBUG_BYTECODE_SUFFIXES
¶
A list of strings representing the file suffixes for non-optimized bytecode modules.
3.3 版新增。
importlib.machinery.
OPTIMIZED_BYTECODE_SUFFIXES
¶
A list of strings representing the file suffixes for optimized bytecode modules.
3.3 版新增。
importlib.machinery.
BYTECODE_SUFFIXES
¶
A list of strings representing the recognized file suffixes for bytecode modules. Set to either
DEBUG_BYTECODE_SUFFIXES
or
OPTIMIZED_BYTECODE_SUFFIXES
based on whether
__debug__
为 True。
3.3 版新增。
importlib.machinery.
EXTENSION_SUFFIXES
¶
A list of strings representing the recognized file suffixes for extension modules.
3.3 版新增。
importlib.machinery.
all_suffixes
(
)
¶
Returns a combined list of strings representing all file suffixes for modules recognized by the standard import machinery. This is a helper for code which simply needs to know if a filesystem path potentially refers to a module without needing any details on the kind of module (for example,
inspect.getmodulename()
).
3.3 版新增。
importlib.machinery.
BuiltinImporter
¶
An
importer
for built-in modules. All known built-in modules are listed in
sys.builtin_module_names
. This class implements the
importlib.abc.MetaPathFinder
and
importlib.abc.InspectLoader
ABCs.
Only class methods are defined by this class to alleviate the need for instantiation.
注意
Due to limitations in the extension module C-API, for now BuiltinImporter does not implement
Loader.exec_module()
.
importlib.machinery.
FrozenImporter
¶
An
importer
for frozen modules. This class implements the
importlib.abc.MetaPathFinder
and
importlib.abc.InspectLoader
ABCs.
Only class methods are defined by this class to alleviate the need for instantiation.
importlib.machinery.
WindowsRegistryFinder
¶
Finder
for modules declared in the Windows registry. This class implements the
importlib.abc.Finder
ABC.
Only class methods are defined by this class to alleviate the need for instantiation.
3.3 版新增。
importlib.machinery.
PathFinder
¶
A
Finder
for
sys.path
和包
__path__
attributes. This class implements the
importlib.abc.MetaPathFinder
ABC.
Only class methods are defined by this class to alleviate the need for instantiation.
find_spec
(
fullname
,
path=None
,
target=None
)
¶
Class method that attempts to find a
spec
for the module specified by
fullname
on
sys.path
or, if defined, on
path
. For each path entry that is searched,
sys.path_importer_cache
is checked. If a non-false object is found then it is used as the
路径条目查找器
to look for the module being searched for. If no entry is found in
sys.path_importer_cache
，那么
sys.path_hooks
is searched for a finder for the path entry and, if found, is stored in
sys.path_importer_cache
along with being queried about the module. If no finder is ever found then
None
is both stored in the cache and returned.
3.4 版新增。
find_module
(
fullname
,
path=None
)
¶
A legacy wrapper around
find_spec()
.
从 3.4 版起弃用：
使用
find_spec()
代替。
invalidate_caches
(
)
¶
调用
importlib.abc.PathEntryFinder.invalidate_caches()
on all finders stored in
sys.path_importer_cache
.
3.4 版改变：
Calls objects in
sys.path_hooks
with the current working directory for
''
(i.e. the empty string).
importlib.machinery.
FileFinder
(
path
,
*loader_details
)
¶
A concrete implementation of
importlib.abc.PathEntryFinder
which caches results from the file system.
The path argument is the directory for which the finder is in charge of searching.
The loader_details argument is a variable number of 2-item tuples each containing a loader and a sequence of file suffixes the loader recognizes. The loaders are expected to be callables which accept two arguments of the module’s name and the path to the file found.
The finder will cache the directory contents as necessary, making stat calls for each module search to verify the cache is not outdated. Because cache staleness relies upon the granularity of the operating system’s state information of the file system, there is a potential race condition of searching for a module, creating a new file, and then searching for the module the new file represents. If the operations happen fast enough to fit within the granularity of stat calls, then the module search will fail. To prevent this from happening, when you create a module dynamically, make sure to call
importlib.invalidate_caches()
.
3.3 版新增。
path
¶
The path the finder will search in.
find_spec
(
fullname
,
target=None
)
¶
Attempt to find the spec to handle
fullname
在
path
.
3.4 版新增。
invalidate_caches
(
)
¶
Clear out the internal cache.
path_hook
(
*loader_details
)
¶
A class method which returns a closure for use on
sys.path_hooks
. An instance of
FileFinder
is returned by the closure using the path argument given to the closure directly and
loader_details
indirectly.
If the argument to the closure is not an existing directory,
ImportError
被引发。
importlib.machinery.
SourceFileLoader
(
fullname
,
path
)
¶
A concrete implementation of
importlib.abc.SourceLoader
by subclassing
importlib.abc.FileLoader
and providing some concrete implementations of other methods.
3.3 版新增。
名称
¶
The name of the module that this loader will handle.
path
¶
源文件路径。
path_stats
(
path
)
¶
set_data
(
path
,
data
)
¶
load_module
(
name=None
)
¶
具体实现的
importlib.abc.Loader.load_module()
where specifying the name of the module to load is optional.
importlib.machinery.
SourcelessFileLoader
(
fullname
,
path
)
¶
A concrete implementation of
importlib.abc.FileLoader
which can import bytecode files (i.e. no source code files exist).
Please note that direct use of bytecode files (and thus not source code files) inhibits your modules from being usable by all Python implementations or new versions of Python which change the bytecode format.
3.3 版新增。
名称
¶
The name of the module the loader will handle.
path
¶
The path to the bytecode file.
get_source
(
fullname
)
¶
返回
None
as bytecode files have no source when this loader is used.
load_module
(
name=None
)
¶
具体实现的
importlib.abc.Loader.load_module()
where specifying the name of the module to load is optional.
importlib.machinery.
ExtensionFileLoader
(
fullname
,
path
)
¶
A concrete implementation of
importlib.abc.ExecutionLoader
for extension modules.
The fullname argument specifies the name of the module the loader is to support. The path argument is the path to the extension module’s file.
3.3 版新增。
名称
¶
Name of the module the loader supports.
path
¶
Path to the extension module.
load_module
(
name=None
)
¶
Loads the extension module if and only if
fullname
如同
name
or is
None
.
注意
Due to limitations in the extension module C-API, for now ExtensionFileLoader does not implement
Loader.exec_module()
.
is_package
(
fullname
)
¶
返回
True
if the file path points to a package’s
__init__
module based on
EXTENSION_SUFFIXES
.
get_code
(
fullname
)
¶
返回
None
as extension modules lack a code object.
get_source
(
fullname
)
¶
返回
None
as extension modules do not have source code.
importlib.machinery.
ModuleSpec
(
name
,
loader
,
*
,
origin=None
,
loader_state=None
,
is_package=None
)
¶
A specification for a module’s import-system-related state.
3.4 版新增。
名称
¶
(
__name__
)
A string for the fully-qualified name of the module.
loader
¶
(
__loader__
)
The loader to use for loading. For namespace packages this should be set to None.
origin
¶
(
__file__
)
Name of the place from which the module is loaded, e.g. “builtin” for built-in modules and the filename for modules loaded from source. Normally “origin” should be set, but it may be None (the default) which indicates it is unspecified.
submodule_search_locations
¶
(
__path__
)
List of strings for where to find submodules, if a package (None otherwise).
loader_state
¶
Container of extra module-specific data for use during loading (or None).
cached
¶
(
__cached__
)
String for where the compiled module should be stored (or None).
parent
¶
(
__package__
)
(Read-only) Fully-qualified name of the package to which the module belongs as a submodule (or None).
has_location
¶
Boolean indicating whether or not the module’s “origin” attribute refers to a loadable location.
importlib.util
– 用于导入器的实用程序代码
¶
This module contains the various objects that help in the construction of an importer .
importlib.util.
MAGIC_NUMBER
¶
The bytes which represent the bytecode version number. If you need help with loading/writing bytecode then consider
importlib.abc.SourceLoader
.
3.4 版新增。
importlib.util.
cache_from_source
(
path
,
debug_override=None
)
¶
返回
PEP 3147
path to the byte-compiled file associated with the source
path
. For example, if
path
is
/foo/bar/baz.py
the return value would be
/foo/bar/__pycache__/baz.cpython-32.pyc
for Python 3.2. The
cpython-32
string comes from the current magic tag (see
get_tag()
；若
sys.implementation.cache_tag
is not defined then
NotImplementedError
will be raised). The returned path will end in
.pyc
当
__debug__
is
True
or
.pyo
for an optimized Python (i.e.
__debug__
is
False
). By passing in
True
or
False
for
debug_override
you can override the system’s value for
__debug__
for extension selection.
path need not exist.
3.4 版新增。
importlib.util.
source_from_cache
(
path
)
¶
Given the
path
到
PEP 3147
file name, return the associated source code file path. For example, if
path
is
/foo/bar/__pycache__/baz.cpython-32.pyc
the returned path would be
/foo/bar/baz.py
.
path
need not exist, however if it does not conform to
PEP 3147
format, a
ValueError
被引发。若
sys.implementation.cache_tag
未定义，
NotImplementedError
被引发。
3.4 版新增。
importlib.util.
decode_source
(
source_bytes
)
¶
Decode the given bytes representing source code and return it as a string with universal newlines (as required by
importlib.abc.InspectLoader.get_source()
).
3.4 版新增。
importlib.util.
resolve_name
(
name
,
package
)
¶
Resolve a relative module name to an absolute one.
若
名称
has no leading dots, then
名称
is simply returned. This allows for usage such as
importlib.util.resolve_name('sys', __package__)
without doing a check to see if the
包
argument is needed.
ValueError
被引发若
名称
is a relative module name but package is a false value (e.g.
None
or the empty string).
ValueError
is also raised a relative name would escape its containing package (e.g. requesting
..bacon
from within the
spam
package).
3.3 版新增。
importlib.util.
find_spec
(
name
,
package=None
)
¶
Find the
spec
for a module, optionally relative to the specified
包
name. If the module is in
sys.modules
，那么
sys.modules[name].__spec__
is returned (unless the spec would be
None
或未设置，在这种情况下
ValueError
被引发)。否则，搜索使用
sys.meta_path
完成。
None
is returned if no spec is found.
若 名称 is for a submodule (contains a dot), the parent module is automatically imported.
名称
and
包
work the same as for
import_module()
.
3.4 版新增。
@
importlib.util.
module_for_loader
¶
A
装饰器
for
importlib.abc.Loader.load_module()
to handle selecting the proper module object to load with. The decorated method is expected to have a call signature taking two positional arguments (e.g.
load_module(self, module)
) for which the second argument will be the module
对象
to be used by the loader. Note that the decorator will not work on static methods because of the assumption of two arguments.
The decorated method will take in the
名称
of the module to be loaded as expected for a
loader
. If the module is not found in
sys.modules
then a new one is constructed. Regardless of where the module came from,
__loader__
设为
self
and
__package__
is set based on what
importlib.abc.InspectLoader.is_package()
returns (if available). These attributes are set unconditionally to support reloading.
If an exception is raised by the decorated method and a module was added to
sys.modules
, then the module will be removed to prevent a partially initialized module from being in left in
sys.modules
. If the module was already in
sys.modules
then it is left alone.
3.3 版改变：
__loader__
and
__package__
are automatically set (when possible).
3.4 版改变：
Set
__name__
,
__loader__
__package__
unconditionally to support reloading.
从 3.4 版起弃用： The import machinery now directly performs all the functionality provided by this function.
@
importlib.util.
set_loader
¶
A
装饰器
for
importlib.abc.Loader.load_module()
to set the
__loader__
attribute on the returned module. If the attribute is already set the decorator does nothing. It is assumed that the first positional argument to the wrapped method (i.e.
self
) is what
__loader__
should be set to.
3.4 版改变：
Set
__loader__
if set to
None
, as if the attribute does not exist.
从 3.4 版起弃用： The import machinery takes care of this automatically.
@
importlib.util.
set_package
¶
A
装饰器
for
importlib.abc.Loader.load_module()
to set the
__package__
attribute on the returned module. If
__package__
is set and has a value other than
None
it will not be changed.
从 3.4 版起弃用： The import machinery takes care of this automatically.
importlib.util.
spec_from_loader
(
name
,
loader
,
*
,
origin=None
,
is_package=None
)
¶
A factory function for creating a
ModuleSpec
instance based on a loader. The parameters have the same meaning as they do for ModuleSpec. The function uses available
loader
APIs, such as
InspectLoader.is_package()
, to fill in any missing information on the spec.
3.4 版新增。
importlib.util.
spec_from_file_location
(
name
,
location
,
*
,
loader=None
,
submodule_search_locations=None
)
¶
A factory function for creating a
ModuleSpec
instance based on the path to a file. Missing information will be filled in on the spec by making use of loader APIs and by the implication that the module will be file-based.
3.4 版新增。