Python模块对象

Single-phase initialization¶

The module initialization function may create and return the module object

directly. This is referred to as "single-phase initialization", and uses one

of the following two module creation functions:

PyObject* PyModule_Create(PyModuleDef *def)¶

Return value: New reference.

Create a new module object, given the definition in def. This behaves

like PyModule_Create2() with module_api_version set to

PYTHON_API_VERSION.

PyObject* PyModule_Create2(PyModuleDef *def, int module_api_version)¶

Return value: New reference.

Create a new module object, given the definition in def, assuming the

API version module_api_version. If that version does not match the version

of the running interpreter, a RuntimeWarning is emitted.

注解

Most uses of this function should be using PyModule_Create()

instead; only use this if you are sure you need it.

Before it is returned from in the initialization function, the resulting module

object is typically populated using functions like PyModule_AddObject().

Multi-phase initialization¶

An alternate way to specify extensions is to request "multi-phase initialization".

Extension modules created this way behave more like Python modules: the

initialization is split between the creation phase, when the module object

is created, and the execution phase, when it is populated.

The distinction is similar to the __new__() and __init__() methods

of classes.

Unlike modules created using single-phase initialization, these modules are not

singletons: if the sys.modules entry is removed and the module is re-imported,

a new module object is created, and the old module is subject to normal garbage

collection -- as with Python modules.

By default, multiple modules created from the same definition should be

independent: changes to one should not affect the others.

This means that all state should be specific to the module object (using e.g.

using PyModule_GetState()), or its contents (such as the module's

__dict__ or individual classes created with PyType_FromSpec()).

All modules created using multi-phase initialization are expected to support

sub-interpreters. Making sure multiple modules

are independent is typically enough to achieve this.

To request multi-phase initialization, the initialization function

(PyInit_modulename) returns a PyModuleDef instance with non-empty

m_slots. Before it is returned, the PyModuleDef

instance must be initialized with the following function:

PyObject* PyModuleDef_Init(PyModuleDef *def)¶

Return value: Borrowed reference.

Ensures a module definition is a properly initialized Python object that

correctly reports its type and reference count.

Returns def cast to PyObject*, or NULL if an error occurred.

3.5 新版功能.

The m_slots member of the module definition must point to an array of

PyModuleDef_Slot structures:

PyModuleDef_Slot¶

int slot¶

A slot ID, chosen from the available values explained below.

void* value¶

Value of the slot, whose meaning depends on the slot ID.

3.5 新版功能.

The m_slots array must be terminated by a slot with id 0.

The available slot types are:

Py_mod_create¶

Specifies a function that is called to create the module object itself.

The value pointer of this slot must point to a function of the signature:

PyObject* create_module(PyObject *spec, PyModuleDef *def)¶

The function receives a ModuleSpec

instance, as defined in PEP 451, and the module definition.

It should return a new module object, or set an error

and return NULL.

This function should be kept minimal. In particular, it should not

call arbitrary Python code, as trying to import the same module again may

result in an infinite loop.

Multiple Py_mod_create slots may not be specified in one module

definition.

If Py_mod_create is not specified, the import machinery will create

a normal module object using PyModule_New(). The name is taken from

spec, not the definition, to allow extension modules to dynamically adjust

to their place in the module hierarchy and be imported under different

names through symlinks, all while sharing a single module definition.

There is no requirement for the returned object to be an instance of

PyModule_Type. Any type can be used, as long as it supports

setting and getting import-related attributes.

However, only PyModule_Type instances may be returned if the

PyModuleDef has non-NULLm_traverse, m_clear,

m_free; non-zero m_size; or slots other than Py_mod_create.

Py_mod_exec¶

Specifies a function that is called to execute the module.

This is equivalent to executing the code of a Python module: typically,

this function adds classes and constants to the module.

The signature of the function is:

int exec_module(PyObject* module)¶

If multiple Py_mod_exec slots are specified, they are processed in the

order they appear in the m_slots array.

See PEP 489 for more details on multi-phase initialization.

Low-level module creation functions¶

The following functions are called under the hood when using multi-phase

initialization. They can be used directly, for example when creating module

objects dynamically. Note that both PyModule_FromDefAndSpec and

PyModule_ExecDef must be called to fully initialize a module.

PyObject * PyModule_FromDefAndSpec(PyModuleDef *def, PyObject *spec)¶

Return value: New reference.

Create a new module object, given the definition in module and the

ModuleSpec spec. This behaves like PyModule_FromDefAndSpec2()

with module_api_version set to PYTHON_API_VERSION.

3.5 新版功能.

PyObject * PyModule_FromDefAndSpec2(PyModuleDef *def, PyObject *spec, int module_api_version)¶

Return value: New reference.

Create a new module object, given the definition in module and the

ModuleSpec spec, assuming the API version module_api_version.

If that version does not match the version of the running interpreter,

a RuntimeWarning is emitted.

注解

Most uses of this function should be using PyModule_FromDefAndSpec()

instead; only use this if you are sure you need it.

3.5 新版功能.

int PyModule_ExecDef(PyObject *module, PyModuleDef *def)¶

Process any execution slots (Py_mod_exec) given in def.

3.5 新版功能.

int PyModule_SetDocString(PyObject *module, const char *docstring)¶

Set the docstring for module to docstring.

This function is called automatically when creating a module from

PyModuleDef, using either PyModule_Create or

PyModule_FromDefAndSpec.

3.5 新版功能.

int PyModule_AddFunctions(PyObject *module, PyMethodDef *functions)¶

Add the functions from the NULL terminated functions array to module.

Refer to the PyMethodDef documentation for details on individual

entries (due to the lack of a shared module namespace, module level

"functions" implemented in C typically receive the module as their first

parameter, making them similar to instance methods on Python classes).

This function is called automatically when creating a module from

PyModuleDef, using either PyModule_Create or

PyModule_FromDefAndSpec.

3.5 新版功能.

Support functions¶

The module initialization function (if using single phase initialization) or

a function called from a module execution slot (if using multi-phase

initialization), can use the following functions to help initialize the module

state:

int PyModule_AddObject(PyObject *module, const char *name, PyObject *value)¶

Add an object to module as name. This is a convenience function which can

be used from the module's initialization function. This steals a reference to

value on success. Return -1 on error, 0 on success.

注解

Unlike other functions that steal references, PyModule_AddObject() only

decrements the reference count of value on success.

This means that its return value must be checked, and calling code must

Py_DECREF()value manually on error. Example usage:

Py_INCREF(spam);
if(PyModule_AddObject(module,"spam",spam)<0){
Py_DECREF(module);
Py_DECREF(spam);
returnNULL;
}

int PyModule_AddIntConstant(PyObject *module, const char *name, long value)¶

Add an integer constant to module as name. This convenience function can be

used from the module's initialization function. Return -1 on error, 0 on

success.

int PyModule_AddStringConstant(PyObject *module, const char *name, const char *value)¶

Add a string constant to module as name. This convenience function can be

used from the module's initialization function. The string value must be

NULL-terminated. Return -1 on error, 0 on success.

int PyModule_AddIntMacro(PyObject *module, macro)¶

Add an int constant to module. The name and the value are taken from

macro. For example PyModule_AddIntMacro(module,AF_INET) adds the int

constant AF_INET with the value of AF_INET to module.

Return -1 on error, 0 on success.

int PyModule_AddStringMacro(PyObject *module, macro)¶

Add a string constant to module.