Introduction¶

The purpose of theimportlib package is three-fold.

One is to provide theimplementation of theimport statement (and thus, by extension, the__import__() function) in Python source code. This provides animplementation ofimport which is portable to any Pythoninterpreter. This also provides an implementation which is easier tocomprehend than one implemented in a programming language other than Python.

Two, the components to implementimport are exposed in thispackage, making it easier for users to create their own custom objects (knowngenerically as animporter) to participate in the import process.

Three, the package contains modules exposing additional functionality formanaging aspects of Python packages:

• importlib.metadata presents access to metadata from third-partydistributions.

• importlib.resources provides routines for accessing non-code“resources” from Python packages.

Functions¶

importlib.__import__(name,globals=None,locals=None,fromlist=(),level=0)¶

An implementation of the built-in__import__() function.

Note

Programmatic importing of modules should useimport_module()instead of this function.

importlib.import_module(name,package=None)¶

Import a module. Thename argument specifies what module toimport in absolute or relative terms(e.g. eitherpkg.mod or..mod). If the name isspecified in relative terms, then thepackage argument must be set tothe name of the package which is to act as the anchor for resolving thepackage name (e.g.import_module('..mod','pkg.subpkg') will importpkg.mod).

Theimport_module() function acts as a simplifying wrapper aroundimportlib.__import__(). This means all semantics of the function arederived fromimportlib.__import__(). The most important differencebetween these two functions is thatimport_module() returns thespecified package or module (e.g.pkg.mod), while__import__()returns the top-level package or module (e.g.pkg).

If you are dynamically importing a module that was created since theinterpreter began execution (e.g., created a Python source file), you mayneed to callinvalidate_caches() in order for the new module to benoticed by the import system.

Changed in version 3.3:Parent packages are automatically imported.

importlib.invalidate_caches()¶

Invalidate the internal caches of finders stored atsys.meta_path. If a finder implementsinvalidate_caches() then itwill be called to perform the invalidation. This function should be calledif any modules are created/installed while your program is running toguarantee all finders will notice the new module’s existence.

Added in version 3.3.

Changed in version 3.10:Namespace packages created/installed in a differentsys.pathlocation after the same namespace was already imported are noticed.

importlib.reload(module)¶

Reload a previously importedmodule. The argument must be a module object,so it must have been successfully imported before. This is useful if youhave edited the module source file using an external editor and want to tryout the new version without leaving the Python interpreter. The return valueis the module object (which can be different if re-importing causes adifferent object to be placed insys.modules).

Whenreload() is executed:

• Python module’s code is recompiled and the module-level code re-executed,defining a new set of objects which are bound to names in the module’sdictionary by reusing theloader which originally loaded themodule. Theinit function of extension modules is not called a secondtime.

• As with all other objects in Python the old objects are only reclaimedafter their reference counts drop to zero.

• The names in the module namespace are updated to point to any new orchanged objects.

• Other references to the old objects (such as names external to the module) arenot rebound to refer to the new objects and must be updated in each namespacewhere they occur if that is desired.

There are a number of other caveats:

When a module is reloaded, its dictionary (containing the module’s globalvariables) is retained. Redefinitions of names will override the olddefinitions, so this is generally not a problem. If the new version of amodule does not define a name that was defined by the old version, the olddefinition remains. This feature can be used to the module’s advantage if itmaintains a global table or cache of objects — with atrystatement it can test for the table’s presence and skip its initialization ifdesired:

try:cacheexceptNameError:cache={}

It is generally not very useful to reload built-in or dynamically loadedmodules. Reloadingsys,__main__,builtins and otherkey modules is not recommended. In many cases extension modules are notdesigned to be initialized more than once, and may fail in arbitrary wayswhen reloaded.

If a module imports objects from another module usingfrom …import …, callingreload() for the other module does notredefine the objects imported from it — one way around this is tore-execute thefrom statement, another is to useimportand qualified names (module.name) instead.

If a module instantiates instances of a class, reloading the module thatdefines the class does not affect the method definitions of the instances —they continue to use the old class definition. The same is true for derivedclasses.

Added in version 3.4.

Changed in version 3.7:ModuleNotFoundError is raised when the module being reloaded lacksaModuleSpec.

importlib.abc – Abstract base classes related to import¶

Source code:Lib/importlib/abc.py

Theimportlib.abc module contains all of the core abstract base classesused byimport. Some subclasses of the core abstract base classesare also provided to help in implementing the core ABCs.

ABC hierarchy:

object+--MetaPathFinder+--PathEntryFinder+--Loader+--ResourceLoader--------++--InspectLoader|+--ExecutionLoader--++--FileLoader+--SourceLoader

classimportlib.abc.MetaPathFinder¶

An abstract base class representing ameta path finder.

Added in version 3.3.

Changed in version 3.10:No longer a subclass ofFinder.

find_spec(fullname,path,target=None)¶

An abstract method for finding aspec forthe specified module. If this is a top-level import,path willbeNone. Otherwise, this is a search for a subpackage ormodule andpath will be the value of__path__ from theparent package. If a spec cannot be found,None is returned.When passed in,target is a module object that the finder mayuse to make a more educated guess about what spec to return.importlib.util.spec_from_loader() may be useful for implementingconcreteMetaPathFinders.

Added in version 3.4.

invalidate_caches()¶

An optional method which, when called, should invalidate any internalcache used by the finder. Used byimportlib.invalidate_caches()when invalidating the caches of all finders onsys.meta_path.

Changed in version 3.4:ReturnsNone when called instead ofNotImplemented.

classimportlib.abc.PathEntryFinder¶

An abstract base class representing apath entry finder. Thoughit bears some similarities toMetaPathFinder,PathEntryFinderis meant for use only within the path-based import subsystem providedbyimportlib.machinery.PathFinder.

Added in version 3.3.

Changed in version 3.10:No longer a subclass ofFinder.

find_spec(fullname,target=None)¶

An abstract method for finding aspec forthe specified module. The finder will search for the module onlywithin thepath entry to which it is assigned. If a speccannot be found,None is returned. When passed in,targetis a module object that the finder may use to make a more educatedguess about what spec to return.importlib.util.spec_from_loader()may be useful for implementing concretePathEntryFinders.

Added in version 3.4.

invalidate_caches()¶

An optional method which, when called, should invalidate any internalcache used by the finder. Used byimportlib.machinery.PathFinder.invalidate_caches()when invalidating the caches of all cached finders.

classimportlib.abc.Loader¶

An abstract base class for aloader.SeePEP 302 for the exact definition for a loader.

Loaders that wish to support resource reading should implement aget_resource_reader() method as specified byimportlib.resources.abc.ResourceReader.

Changed in version 3.7:Introduced the optionalget_resource_reader() method.

create_module(spec)¶

A method that returns the module object to use whenimporting a module. This method may returnNone,indicating that default module creation semantics should take place.

Added in version 3.4.

Changed in version 3.6:This method is no longer optional whenexec_module() is defined.

exec_module(module)¶

An abstract method that executes the module in its own namespacewhen a module is imported or reloaded. The module should alreadybe initialized whenexec_module() is called. When this method exists,create_module() must be defined.

Added in version 3.4.

Changed in version 3.6:create_module() must also be defined.

load_module(fullname)¶

A legacy method for loading a module. If the module cannot beloaded,ImportError is raised, otherwise the loaded module isreturned.

If the requested module already exists insys.modules, thatmodule should be used and reloaded.Otherwise the loader should create a new module and insert it intosys.modules before any loading begins, to prevent recursionfrom the import. If the loader inserted a module and the load fails, itmust be removed by the loader fromsys.modules; modules alreadyinsys.modules before the loader began execution should be leftalone.

The loader should set several attributes on the module(note that some of these attributes can change when a module isreloaded):

• module.__name__

• module.__file__

• module.__cached__(deprecated)

• module.__path__

• module.__package__(deprecated)

• module.__loader__(deprecated)

Whenexec_module() is available then backwards-compatiblefunctionality is provided.

Changed in version 3.4:RaiseImportError when called instead ofNotImplementedError. Functionality provided whenexec_module() is available.

Deprecated since version 3.4, will be removed in version 3.15:The recommended API for loading a module isexec_module()(andcreate_module()). Loaders should implement it instead ofload_module(). The import machinery takes care of all theother responsibilities ofload_module() whenexec_module() is implemented.

classimportlib.abc.ResourceLoader¶

Superseded by TraversableResources

An abstract base class for aloader which implements the optionalPEP 302 protocol for loading arbitrary resources from the storageback-end.

Deprecated since version 3.7:This ABC is deprecated in favour of supporting resource loadingthroughimportlib.resources.abc.TraversableResources.

abstractmethodget_data(path)¶

An abstract method to return the bytes for the data located atpath.Loaders that have a file-like storage back-endthat allows storing arbitrary datacan implement this abstract method to give direct accessto the data stored.OSError is to be raised if thepath cannotbe found. Thepath is expected to be constructed using a module’s__file__ attribute or an item from a package’s__path__.

Changed in version 3.4:RaisesOSError instead ofNotImplementedError.

classimportlib.abc.InspectLoader¶

An abstract base class for aloader which implements the optionalPEP 302 protocol for loaders that inspect modules.

get_code(fullname)¶

Return the code object for a module, orNone if the module does nothave a code object (as would be the case, for example, for a built-inmodule). Raise anImportError if loader cannot find therequested module.

Note

While the method has a default implementation, it is suggested thatit be overridden if possible for performance.

Changed in version 3.4:No longer abstract and a concrete implementation is provided.

abstractmethodget_source(fullname)¶

An abstract method to return the source of a module. It is returned asa text string usinguniversal newlines, translating allrecognized line separators into'\n' characters. ReturnsNoneif no source is available (e.g. a built-in module). RaisesImportError if the loader cannot find the module specified.

Changed in version 3.4:RaisesImportError instead ofNotImplementedError.

is_package(fullname)¶

An optional method to return a true value if the module is a package, afalse value otherwise.ImportError is raised if theloader cannot find the module.

Changed in version 3.4:RaisesImportError instead ofNotImplementedError.

staticsource_to_code(data,path='<string>')¶

Create a code object from Python source.

Thedata argument can be whatever thecompile() functionsupports (i.e. string or bytes). Thepath argument should bethe “path” to where the source code originated from, which can be anabstract concept (e.g. location in a zip file).

With the subsequent code object one can execute it in a module byrunningexec(code,module.__dict__).

Added in version 3.4.

Changed in version 3.5:Made the method static.

exec_module(module)¶

Implementation ofLoader.exec_module().

Added in version 3.4.

load_module(fullname)¶

Implementation ofLoader.load_module().

Deprecated since version 3.4, will be removed in version 3.15:useexec_module() instead.

classimportlib.abc.ExecutionLoader¶

An abstract base class which inherits fromInspectLoader that,when implemented, helps a module to be executed as a script. The ABCrepresents an optionalPEP 302 protocol.

abstractmethodget_filename(fullname)¶

An abstract method that is to return the value of__file__ for the specified module. If no path isavailable,ImportError is raised.

If source code is available, then the method should return the path tothe source file, regardless of whether a bytecode was used to load themodule.

Changed in version 3.4:RaisesImportError instead ofNotImplementedError.

classimportlib.abc.FileLoader(fullname,path)¶

An abstract base class which inherits fromResourceLoader andExecutionLoader, providing concrete implementations ofResourceLoader.get_data() andExecutionLoader.get_filename().

Thefullname argument is a fully resolved name of the module the loader isto handle. Thepath argument is the path to the file for the module.

Added in version 3.3.

name¶

The name of the module the loader can handle.

path¶

Path to the file of the module.

load_module(fullname)¶

Calls super’sload_module().

Deprecated since version 3.4, will be removed in version 3.15:UseLoader.exec_module() instead.

abstractmethodget_filename(fullname)¶

Returnspath.

abstractmethodget_data(path)¶

Readspath as a binary file and returns the bytes from it.

classimportlib.abc.SourceLoader¶

An abstract base class for implementing source (and optionally bytecode)file loading. The class inherits from bothResourceLoader andExecutionLoader, requiring the implementation of:

• ResourceLoader.get_data()

• ExecutionLoader.get_filename()

  Should only return the path to the source file; sourcelessloading is not supported.

The abstract methods defined by this class are to add optional bytecodefile support. Not implementing these optional methods (or causing them toraiseNotImplementedError) causes the loader toonly work with source code. Implementing the methods allows the loader towork with sourceand bytecode files; it does not allow forsourcelessloading where only bytecode is provided. Bytecode files are anoptimization to speed up loading by removing the parsing step of Python’scompiler, and so no bytecode-specific API is exposed.

path_stats(path)¶

Optional abstract method which returns adict containingmetadata about the specified path. Supported dictionary keys are:

• 'mtime' (mandatory): an integer or floating-point numberrepresenting 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 futureextensions. If the path cannot be handled,OSError is raised.

Added in version 3.3.

Changed in version 3.4:RaiseOSError instead ofNotImplementedError.

path_mtime(path)¶

Optional abstract method which returns the modification time for thespecified path.

Deprecated since version 3.3:This method is deprecated in favour ofpath_stats(). You don’thave to implement it, but it is still available for compatibilitypurposes. RaiseOSError if the path cannot be handled.

Changed in version 3.4:RaiseOSError instead ofNotImplementedError.

set_data(path,data)¶

Optional abstract method which writes the specified bytes to a filepath. Any intermediate directories which do not exist are to be createdautomatically.

When writing to the path fails because the path is read-only(errno.EACCES/PermissionError), do not propagate theexception.

Changed in version 3.4:No longer raisesNotImplementedError when called.

get_code(fullname)¶

Concrete implementation ofInspectLoader.get_code().

exec_module(module)¶

Concrete implementation ofLoader.exec_module().

Added in version 3.4.

load_module(fullname)¶

Concrete implementation ofLoader.load_module().

Deprecated since version 3.4, will be removed in version 3.15:Useexec_module() instead.

get_source(fullname)¶

Concrete implementation ofInspectLoader.get_source().

is_package(fullname)¶

Concrete implementation ofInspectLoader.is_package(). A moduleis determined to be a package if its file path (as provided byExecutionLoader.get_filename()) is a file named__init__ when the file extension is removedand the module nameitself does not end in__init__.

classimportlib.abc.ResourceReader¶

Superseded by TraversableResources

Anabstract base class to provide the ability to readresources.

From the perspective of this ABC, aresource is a binaryartifact that is shipped within a package. Typically this issomething like a data file that lives next to the__init__.pyfile of the package. The purpose of this class is to help abstractout the accessing of such data files so that it does not matter ifthe package and its data file(s) are stored e.g. in a zip fileversus on the file system.

For any of methods of this class, aresource argument isexpected to be apath-like object which representsconceptually just a file name. This means that no subdirectorypaths should be included in theresource argument. This isbecause the location of the package the reader is for, acts as the“directory”. Hence the metaphor for directories and filenames is packages and resources, respectively. This is also whyinstances of this class are expected to directly correlate toa specific package (instead of potentially representing multiplepackages or a module).

Loaders that wish to support resource reading are expected toprovide a method calledget_resource_reader(fullname) whichreturns an object implementing this ABC’s interface. If the modulespecified by fullname is not a package, this method should returnNone. An object compatible with this ABC should only bereturned when the specified module is a package.

Added in version 3.7.

Deprecated since version 3.12, will be removed in version 3.14:Useimportlib.resources.abc.TraversableResources instead.

abstractmethodopen_resource(resource)¶

Returns an opened,file-like object for binary readingof theresource.

If the resource cannot be found,FileNotFoundError israised.

abstractmethodresource_path(resource)¶

Returns the file system path to theresource.

If the resource does not concretely exist on the file system,raiseFileNotFoundError.

abstractmethodis_resource(name)¶

ReturnsTrue if the namedname is considered a resource.FileNotFoundError is raised ifname does not exist.

abstractmethodcontents()¶

Returns aniterable of strings over the contents ofthe package. Do note that it is not required that all namesreturned by the iterator be actual resources, e.g. it isacceptable to return names for whichis_resource() wouldbe false.

Allowing non-resource names to be returned is to allow forsituations where how a package and its resources are storedare known a priori and the non-resource names would be useful.For instance, returning subdirectory names is allowed so thatwhen it is known that the package and resources are stored onthe file system then those subdirectory names can be useddirectly.

The abstract method returns an iterable of no items.

classimportlib.abc.Traversable¶

An object with a subset ofpathlib.Path methods suitable fortraversing directories and opening files.

For a representation of the object on the file-system, useimportlib.resources.as_file().

Added in version 3.9.

Deprecated since version 3.12, will be removed in version 3.14:Useimportlib.resources.abc.Traversable instead.

name¶

Abstract. The base name of this object without any parent references.

abstractmethoditerdir()¶

YieldTraversable objects inself.

abstractmethodis_dir()¶

ReturnTrue ifself is a directory.

abstractmethodis_file()¶

ReturnTrue ifself is a file.

abstractmethodjoinpath(child)¶

Return Traversable child inself.

abstractmethod__truediv__(child)¶

ReturnTraversable child inself.

abstractmethodopen(mode='r',*args,**kwargs)¶

mode may be ‘r’ or ‘rb’ to open as text or binary. Return a handlesuitable for reading (same aspathlib.Path.open).

When opening as text, accepts encoding parameters such as thoseaccepted byio.TextIOWrapper.

read_bytes()¶

Read contents ofself as bytes.

read_text(encoding=None)¶

Read contents ofself as text.

classimportlib.abc.TraversableResources¶

An abstract base class for resource readers capable of servingtheimportlib.resources.files() interface. Subclassesimportlib.resources.abc.ResourceReader and providesconcrete implementations of theimportlib.resources.abc.ResourceReader’sabstract methods. Therefore, any loader supplyingimportlib.abc.TraversableResources also supplies ResourceReader.

Loaders that wish to support resource reading are expected toimplement this interface.

Added in version 3.9.

Deprecated since version 3.12, will be removed in version 3.14:Useimportlib.resources.abc.TraversableResources instead.

abstractmethodfiles()¶

Returns aimportlib.resources.abc.Traversable object for the loadedpackage.

importlib.machinery – Importers and path hooks¶

Source code:Lib/importlib/machinery.py

This module contains the various objects that helpimportfind and load modules.

importlib.machinery.SOURCE_SUFFIXES¶

A list of strings representing the recognized file suffixes for sourcemodules.

Added in version 3.3.

importlib.machinery.DEBUG_BYTECODE_SUFFIXES¶

A list of strings representing the file suffixes for non-optimized bytecodemodules.

Added in version 3.3.

Deprecated since version 3.5:UseBYTECODE_SUFFIXES instead.

importlib.machinery.OPTIMIZED_BYTECODE_SUFFIXES¶

A list of strings representing the file suffixes for optimized bytecodemodules.

Added in version 3.3.

Deprecated since version 3.5:UseBYTECODE_SUFFIXES instead.

importlib.machinery.BYTECODE_SUFFIXES¶

A list of strings representing the recognized file suffixes for bytecodemodules (including the leading dot).

Added in version 3.3.

Changed in version 3.5:The value is no longer dependent on__debug__.

importlib.machinery.EXTENSION_SUFFIXES¶

A list of strings representing the recognized file suffixes forextension modules.

Added in version 3.3.

importlib.machinery.all_suffixes()¶

Returns a combined list of strings representing all file suffixes formodules recognized by the standard import machinery. This is ahelper for code which simply needs to know if a filesystem pathpotentially refers to a module without needing any details on the kindof module (for example,inspect.getmodulename()).

Added in version 3.3.

classimportlib.machinery.BuiltinImporter¶

Animporter for built-in modules. All known built-in modules arelisted insys.builtin_module_names. This class implements theimportlib.abc.MetaPathFinder andimportlib.abc.InspectLoader ABCs.

Only class methods are defined by this class to alleviate the need forinstantiation.

Changed in version 3.5:As part ofPEP 489, the builtin importer now implementsLoader.create_module() andLoader.exec_module()

classimportlib.machinery.FrozenImporter¶

Animporter for frozen modules. This class implements theimportlib.abc.MetaPathFinder andimportlib.abc.InspectLoader ABCs.

Only class methods are defined by this class to alleviate the need forinstantiation.

Changed in version 3.4:Gainedcreate_module() andexec_module()methods.

classimportlib.machinery.WindowsRegistryFinder¶

Finder for modules declared in the Windows registry. This classimplements theimportlib.abc.MetaPathFinder ABC.

Only class methods are defined by this class to alleviate the need forinstantiation.

Added in version 3.3.

Deprecated since version 3.6:Usesite configuration instead. Future versions of Python maynot enable this finder by default.

classimportlib.machinery.PathFinder¶

AFinder forsys.path and package__path__ attributes.This class implements theimportlib.abc.MetaPathFinder ABC.

Only class methods are defined by this class to alleviate the need forinstantiation.

classmethodfind_spec(fullname,path=None,target=None)¶

Class method that attempts to find aspecfor the module specified byfullname onsys.path or, ifdefined, onpath. For each path entry that is searched,sys.path_importer_cache is checked. If a non-false objectis found then it is used as thepath entry finder to lookfor the module being searched for. If no entry is found insys.path_importer_cache, thensys.path_hooks issearched for a finder for the path entry and, if found, is storedinsys.path_importer_cache along with being queried aboutthe module. If no finder is ever found thenNone is bothstored in the cache and returned.

Added in version 3.4.

Changed in version 3.5:If the current working directory – represented by an empty string –is no longer valid thenNone is returned but no value is cachedinsys.path_importer_cache.

classmethodinvalidate_caches()¶

Callsimportlib.abc.PathEntryFinder.invalidate_caches() on allfinders stored insys.path_importer_cache that define the method.Otherwise entries insys.path_importer_cache set toNone aredeleted.

Changed in version 3.7:Entries ofNone insys.path_importer_cache are deleted.

Changed in version 3.4:Calls objects insys.path_hooks with the current workingdirectory for'' (i.e. the empty string).

classimportlib.machinery.FileFinder(path,*loader_details)¶

A concrete implementation ofimportlib.abc.PathEntryFinder whichcaches results from the file system.

Thepath argument is the directory for which the finder is in charge ofsearching.

Theloader_details argument is a variable number of 2-item tuples eachcontaining a loader and a sequence of file suffixes the loader recognizes.The loaders are expected to be callables which accept two arguments ofthe module’s name and the path to the file found.

The finder will cache the directory contents as necessary, making stat callsfor each module search to verify the cache is not outdated. Because cachestaleness relies upon the granularity of the operating system’s stateinformation of the file system, there is a potential race condition ofsearching for a module, creating a new file, and then searching for themodule the new file represents. If the operations happen fast enough to fitwithin the granularity of stat calls, then the module search will fail. Toprevent this from happening, when you create a module dynamically, make sureto callimportlib.invalidate_caches().

Added in version 3.3.

path¶

The path the finder will search in.

find_spec(fullname,target=None)¶

Attempt to find the spec to handlefullname withinpath.

Added in version 3.4.

invalidate_caches()¶

Clear out the internal cache.

classmethodpath_hook(*loader_details)¶

A class method which returns a closure for use onsys.path_hooks.An instance ofFileFinder is returned by the closure using thepath argument given to the closure directly andloader_detailsindirectly.

If the argument to the closure is not an existing directory,ImportError is raised.

classimportlib.machinery.SourceFileLoader(fullname,path)¶

A concrete implementation ofimportlib.abc.SourceLoader bysubclassingimportlib.abc.FileLoader and providing some concreteimplementations of other methods.

Added in version 3.3.

name¶

The name of the module that this loader will handle.

path¶

The path to the source file.

is_package(fullname)¶

ReturnTrue ifpath appears to be for a package.

path_stats(path)¶

Concrete implementation ofimportlib.abc.SourceLoader.path_stats().

set_data(path,data)¶

Concrete implementation ofimportlib.abc.SourceLoader.set_data().

load_module(name=None)¶

Concrete implementation ofimportlib.abc.Loader.load_module() wherespecifying the name of the module to load is optional.

Deprecated since version 3.6, will be removed in version 3.15:Useimportlib.abc.Loader.exec_module() instead.

classimportlib.machinery.SourcelessFileLoader(fullname,path)¶

A concrete implementation ofimportlib.abc.FileLoader which canimport bytecode files (i.e. no source code files exist).

Please note that direct use of bytecode files (and thus not source codefiles) inhibits your modules from being usable by all Pythonimplementations or new versions of Python which change the bytecodeformat.

Added in version 3.3.

name¶

The name of the module the loader will handle.

path¶

The path to the bytecode file.

is_package(fullname)¶

Determines if the module is a package based onpath.

get_code(fullname)¶

Returns the code object forname created frompath.

get_source(fullname)¶

ReturnsNone as bytecode files have no source when this loader isused.

load_module(name=None)¶

Concrete implementation ofimportlib.abc.Loader.load_module() wherespecifying the name of the module to load is optional.

Deprecated since version 3.6, will be removed in version 3.15:Useimportlib.abc.Loader.exec_module() instead.

classimportlib.machinery.ExtensionFileLoader(fullname,path)¶

A concrete implementation ofimportlib.abc.ExecutionLoader forextension modules.

Thefullname argument specifies the name of the module the loader is tosupport. Thepath argument is the path to the extension module’s file.

Note that, by default, importing an extension module will failin subinterpreters if it doesn’t implement multi-phase init(seePEP 489), even if it would otherwise import successfully.

Added in version 3.3.

Changed in version 3.12:Multi-phase init is now required for use in subinterpreters.

name¶

Name of the module the loader supports.

path¶

Path to the extension module.

create_module(spec)¶

Creates the module object from the given specification in accordancewithPEP 489.

Added in version 3.5.

exec_module(module)¶

Initializes the given module object in accordance withPEP 489.

Added in version 3.5.

is_package(fullname)¶

ReturnsTrue if the file path points to a package’s__init__module based onEXTENSION_SUFFIXES.

get_code(fullname)¶

ReturnsNone as extension modules lack a code object.

get_source(fullname)¶

ReturnsNone as extension modules do not have source code.

get_filename(fullname)¶

Returnspath.

Added in version 3.4.

classimportlib.machinery.NamespaceLoader(name,path,path_finder)¶

A concrete implementation ofimportlib.abc.InspectLoader fornamespace packages. This is an alias for a private class and is only madepublic for introspecting the__loader__ attribute on namespacepackages:

>>>fromimportlib.machineryimportNamespaceLoader>>>importmy_namespace>>>isinstance(my_namespace.__loader__,NamespaceLoader)True>>>importimportlib.abc>>>isinstance(my_namespace.__loader__,importlib.abc.Loader)True

Added in version 3.11.

classimportlib.machinery.ModuleSpec(name,loader,*,origin=None,loader_state=None,is_package=None)¶

A specification for a module’s import-system-related state. This istypically exposed as the module’s__spec__ attribute. Manyof these attributes are also available directly on a module: for example,module.__spec__.origin==module.__file__. Note, however, thatwhile thevalues are usually equivalent, they can differ since there isno synchronization between the two objects. For example, it is possible toupdate the module’s__file__ at runtime and this will not beautomatically reflected in the module’s__spec__.origin, and vice versa.

Added in version 3.4.

name¶

The module’s fully qualified name (seemodule.__name__).Thefinder should always set this attribute to a non-empty string.

loader¶

Theloader used to load the module (seemodule.__loader__).Thefinder should always set this attribute.

origin¶

The location theloader should use to load the module(seemodule.__file__).For example, for modules loaded from a.py file this is the filename.Thefinder should always set this attribute to a meaningful valuefor theloader to use. In the uncommon case that there is not one(like for namespace packages), it should be set toNone.

submodule_search_locations¶

A (possibly empty)sequence of strings enumerating the locationsin which a package’s submodules will be found(seemodule.__path__). Most of the time there will only be asingle directory in this list.

Thefinder should set this attribute to a sequence, even an emptyone, to indicateto the import system that the module is a package. It should be set toNone fornon-package modules. It is set automatically later to a special object fornamespace packages.

loader_state¶

Thefinder may set this attribute to an object containing additional,module-specific data to use when loading the module. Otherwise it should beset toNone.

cached¶

The filename of a compiled version of the module’s code(seemodule.__cached__).Thefinder should always set this attribute but it may beNonefor modules that do not need compiled code stored.

parent¶

(Read-only) The fully qualified name of the package the module is in (or theempty string for a top-level module).Seemodule.__package__.If the module is a package then this is the same asname.

has_location¶

True if the spec’sorigin refers to a loadable location,False otherwise. This value impacts howorigin is interpretedand how the module’s__file__ is populated.

classimportlib.machinery.AppleFrameworkLoader(name,path)¶

A specialization ofimportlib.machinery.ExtensionFileLoader thatis able to load extension modules in Framework format.

For compatibility with the iOS App Store,all binary modules in an iOS appmust be dynamic libraries, contained in a framework with appropriatemetadata, stored in theFrameworks folder of the packaged app. There canbe only a single binary per framework, and there can be no executable binarymaterial outside the Frameworks folder.

To accommodate this requirement, when running on iOS, extension modulebinaries arenot packaged as.so files onsys.path, but asindividual standalone frameworks. To discover those frameworks, this loaderis be registered against the.fwork file extension, with a.fworkfile acting as a placeholder in the original location of the binary onsys.path. The.fwork file contains the path of the actual binary intheFrameworks folder, relative to the app bundle. To allow forresolving a framework-packaged binary back to the original location, theframework is expected to contain a.origin file that contains thelocation of the.fwork file, relative to the app bundle.

For example, consider the case of an importfromfoo.barimport_whiz,where_whiz is implemented with the binary modulesources/foo/bar/_whiz.abi3.so, withsources being the locationregistered onsys.path, relative to the application bundle. This modulemust be distributed asFrameworks/foo.bar._whiz.framework/foo.bar._whiz (creating the frameworkname from the full import path of the module), with anInfo.plist filein the.framework directory identifying the binary as a framework. Thefoo.bar._whiz module would be represented in the original location withasources/foo/bar/_whiz.abi3.fwork marker file, containing the pathFrameworks/foo.bar._whiz/foo.bar._whiz. The framework would also containFrameworks/foo.bar._whiz.framework/foo.bar._whiz.origin, containing thepath to the.fwork file.

When a module is loaded with this loader, the__file__ for the modulewill report as the location of the.fwork file. This allows code to usethe__file__ of a module as an anchor for file system traveral.However, the spec origin will reference the location of theactual binaryin the.framework folder.

The Xcode project building the app is responsible for converting any.sofiles from wherever they exist in thePYTHONPATH into frameworks in theFrameworks folder (including stripping extensions from the module file,the addition of framework metadata, and signing the resulting framework),and creating the.fwork and.origin files. This will usually be donewith a build step in the Xcode project; see the iOS documentation fordetails on how to construct this build step.

Added in version 3.13.

Availability: iOS.

name¶

Name of the module the loader supports.

path¶

Path to the.fwork file for the extension module.

importlib.util – Utility code for importers¶

Source code:Lib/importlib/util.py

This module contains the various objects that help in the construction ofanimporter.

importlib.util.MAGIC_NUMBER¶

The bytes which represent the bytecode version number. If you need help withloading/writing bytecode then considerimportlib.abc.SourceLoader.

Added in version 3.4.

importlib.util.cache_from_source(path,debug_override=None,*,optimization=None)¶

Return thePEP 3147/PEP 488 path to the byte-compiled file associatedwith the sourcepath. For example, ifpath is/foo/bar/baz.py the returnvalue would be/foo/bar/__pycache__/baz.cpython-32.pyc for Python 3.2.Thecpython-32 string comes from the current magic tag (seeget_tag(); ifsys.implementation.cache_tag is not defined thenNotImplementedError will be raised).

Theoptimization parameter is used to specify the optimization level of thebytecode file. An empty string represents no optimization, so/foo/bar/baz.py with anoptimization of'' will result in abytecode path of/foo/bar/__pycache__/baz.cpython-32.pyc.None causesthe interpreter’s optimization level to be used. Any other value’s stringrepresentation is used, so/foo/bar/baz.py with anoptimization of2 will lead to the bytecode path of/foo/bar/__pycache__/baz.cpython-32.opt-2.pyc. The string representationofoptimization can only be alphanumeric, elseValueError is raised.

Thedebug_override parameter is deprecated and can be used to overridethe system’s value for__debug__. ATrue value is the equivalent ofsettingoptimization to the empty string. AFalse value is the same assettingoptimization to1. If bothdebug_override anoptimizationare notNone thenTypeError is raised.

Added in version 3.4.

Changed in version 3.5:Theoptimization parameter was added and thedebug_override parameterwas deprecated.

Changed in version 3.6:Accepts apath-like object.

importlib.util.source_from_cache(path)¶

Given thepath to aPEP 3147 file name, return the associated source codefile path. For example, ifpath 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 conformtoPEP 3147 orPEP 488 format, aValueError is raised. Ifsys.implementation.cache_tag is not defined,NotImplementedError is raised.

Added in version 3.4.

Changed in version 3.6:Accepts apath-like object.

importlib.util.decode_source(source_bytes)¶

Decode the given bytes representing source code and return it as a stringwith universal newlines (as required byimportlib.abc.InspectLoader.get_source()).

Added in version 3.4.

importlib.util.resolve_name(name,package)¶

Resolve a relative module name to an absolute one.

Ifname has no leading dots, thenname is simply returned. Thisallows for usage such asimportlib.util.resolve_name('sys',__spec__.parent) without doing acheck to see if thepackage argument is needed.

ImportError is raised ifname is a relative module name butpackage is a false value (e.g.None or the empty string).ImportError is also raised if a relative name would escape itscontaining package (e.g. requesting..bacon from within thespampackage).

Added in version 3.3.

Changed in version 3.9:To improve consistency with import statements, raiseImportError instead ofValueError for invalid relativeimport attempts.

importlib.util.find_spec(name,package=None)¶

Find thespec for a module, optionally relative tothe specifiedpackage name. If the module is insys.modules,thensys.modules[name].__spec__ is returned (unless the spec would beNone or is not set, in which caseValueError is raised).Otherwise a search usingsys.meta_path is done.None isreturned if no spec is found.

Ifname is for a submodule (contains a dot), the parent module isautomatically imported.

name andpackage work the same as forimport_module().

Added in version 3.4.

Changed in version 3.7:RaisesModuleNotFoundError instead ofAttributeError ifpackage is in fact not a package (i.e. lacks a__path__ attribute).

importlib.util.module_from_spec(spec)¶

Create a new module based onspec andspec.loader.create_module.

Ifspec.loader.create_moduledoes not returnNone, then any pre-existing attributes will not be reset.Also, noAttributeError will be raised if triggered while accessingspec or setting an attribute on the module.

This function is preferred over usingtypes.ModuleType to create anew module asspec is used to set as many import-controlled attributes onthe module as possible.

Added in version 3.5.

importlib.util.spec_from_loader(name,loader,*,origin=None,is_package=None)¶

A factory function for creating aModuleSpecinstance based on a loader. The parameters have the same meaning as they dofor ModuleSpec. The function uses availableloader APIs, such asInspectLoader.is_package(), to fill in any missinginformation on the spec.

Added in version 3.4.

importlib.util.spec_from_file_location(name,location,*,loader=None,submodule_search_locations=None)¶

A factory function for creating aModuleSpecinstance based on the path to a file. Missing information will be filled inon the spec by making use of loader APIs and by the implication that themodule will be file-based.

Added in version 3.4.

Changed in version 3.6:Accepts apath-like object.

importlib.util.source_hash(source_bytes)¶

Return the hash ofsource_bytes as bytes. A hash-based.pyc file embedsthesource_hash() of the corresponding source file’s contents in itsheader.

Added in version 3.7.

importlib.util._incompatible_extension_module_restrictions(*,disable_check)¶

A context manager that can temporarily skip the compatibility checkfor extension modules. By default the check is enabled and will failwhen a single-phase init module is imported in a subinterpreter.It will also fail for a multi-phase init module that doesn’texplicitly support a per-interpreter GIL, when importedin an interpreter with its own GIL.

Note that this function is meant to accommodate an unusual case;one which is likely to eventually go away. There’s is a pretty goodchance this is not what you were looking for.

You can get the same effect as this function by implementing thebasic interface of multi-phase init (PEP 489) and lying aboutsupport for multiple interpreters (or per-interpreter GIL).

Warning

Using this function to disable the check can lead tounexpected behavior and even crashes. It should only be used duringextension module development.

Added in version 3.12.

classimportlib.util.LazyLoader(loader)¶

A class which postpones the execution of the loader of a module until themodule has an attribute accessed.

This classonly works with loaders that defineexec_module() as control over what module typeis used for the module is required. For those same reasons, the loader’screate_module() method must returnNone or atype for which its__class__ attribute can be mutated along with notusingslots. Finally, modules which substitute the objectplaced intosys.modules will not work as there is no way to properlyreplace the module references throughout the interpreter safely;ValueError is raised if such a substitution is detected.

Note

For projects where startup time is critical, this class allows forpotentially minimizing the cost of loading a module if it is never used.For projects where startup time is not essential then use of this class isheavily discouraged due to error messages created during loading beingpostponed and thus occurring out of context.

Added in version 3.5.

Changed in version 3.6:Began callingcreate_module(), removing thecompatibility warning forimportlib.machinery.BuiltinImporter andimportlib.machinery.ExtensionFileLoader.

classmethodfactory(loader)¶

A class method which returns a callable that creates a lazy loader. Thisis meant to be used in situations where the loader is passed by classinstead of by instance.

suffixes=importlib.machinery.SOURCE_SUFFIXESloader=importlib.machinery.SourceFileLoaderlazy_loader=importlib.util.LazyLoader.factory(loader)finder=importlib.machinery.FileFinder(path,(lazy_loader,suffixes))

Examples¶

importimportlibitertools=importlib.import_module('itertools')

importimportlib.utilimportsys# For illustrative purposes.name='itertools'ifnameinsys.modules:print(f"{name!r} already in sys.modules")elif(spec:=importlib.util.find_spec(name))isnotNone:# If you chose to perform the actual import ...module=importlib.util.module_from_spec(spec)sys.modules[name]=modulespec.loader.exec_module(module)print(f"{name!r} has been imported")else:print(f"can't find the{name!r} module")

importimportlib.utilimportsysdefimport_from_path(module_name,file_path):spec=importlib.util.spec_from_file_location(module_name,file_path)module=importlib.util.module_from_spec(spec)sys.modules[module_name]=modulespec.loader.exec_module(module)returnmodule# For illustrative purposes only (use of `json` is arbitrary).importjsonfile_path=json.__file__module_name=json.__name__# Similar outcome as `import json`.json=import_from_path(module_name,file_path)

>>>importimportlib.util>>>importsys>>>deflazy_import(name):...spec=importlib.util.find_spec(name)...loader=importlib.util.LazyLoader(spec.loader)...spec.loader=loader...module=importlib.util.module_from_spec(spec)...sys.modules[name]=module...loader.exec_module(module)...returnmodule...>>>lazy_typing=lazy_import("typing")>>>#lazy_typing is a real module object,>>>#but it is not loaded in memory yet.>>>lazy_typing.TYPE_CHECKINGFalse

importimportlib.machineryimportsys# For illustrative purposes only.SpamMetaPathFinder=importlib.machinery.PathFinderSpamPathEntryFinder=importlib.machinery.FileFinderloader_details=(importlib.machinery.SourceFileLoader,importlib.machinery.SOURCE_SUFFIXES)# Setting up a meta path finder.# Make sure to put the finder in the proper location in the list in terms of# priority.sys.meta_path.append(SpamMetaPathFinder)# Setting up a path entry finder.# Make sure to put the path hook in the proper location in the list in terms# of priority.sys.path_hooks.append(SpamPathEntryFinder.path_hook(loader_details))

importimportlib.utilimportsysdefimport_module(name,package=None):"""An approximate implementation of import."""absolute_name=importlib.util.resolve_name(name,package)try:returnsys.modules[absolute_name]exceptKeyError:passpath=Noneif'.'inabsolute_name:parent_name,_,child_name=absolute_name.rpartition('.')parent_module=import_module(parent_name)path=parent_module.__spec__.submodule_search_locationsforfinderinsys.meta_path:spec=finder.find_spec(absolute_name,path)ifspecisnotNone:breakelse:msg=f'No module named{absolute_name!r}'raiseModuleNotFoundError(msg,name=absolute_name)module=importlib.util.module_from_spec(spec)sys.modules[absolute_name]=modulespec.loader.exec_module(module)ifpathisnotNone:setattr(parent_module,child_name,module)returnmodule