PyModule_Type
Part of the
.This instance of
represents the Python module type. This is exposed to Python programs as
.
intPyModule_Check(
*p)
Return true if p is a module object, or a subtype of a module object. This function always succeeds.
intPyModule_CheckExact(
*p)
Return true if p is a module object, but not a subtype of
. This function always succeeds.
*PyModule_NewObject(
*name)
Return value: New reference. Part of the
since version 3.7.Return a new module object with
set to name. The module’s __name__,
,
and
attributes are filled in (all but __name__ are set to None). The caller is responsible for setting a
attribute.
Return NULL with an exception set on error.
Added in version 3.3.
*PyModule_New(constchar*name)
Return value: New reference. Part of the
.Similar to
, but the name is a UTF-8 encoded string instead of a Unicode object.
*PyModule_GetDict(
*module)
Return value: Borrowed reference. Part of the
.Return the dictionary object that implements module’s namespace; this object is the same as the
attribute of the module object. If module is not a module object (or a subtype of a module object),
is raised and NULL is returned.
It is recommended extensions use other PyModule_* and PyObject_* functions rather than directly manipulate a module’s
.
The returned reference is borrowed from the module; it is valid until the module is destroyed.
*PyModule_GetNameObject(
*module)
Return value: New reference. Part of the
since version 3.7.Return module’s
value. If the module does not provide one, or if it is not a string,
is raised and NULL is returned.
Added in version 3.3.
constchar*PyModule_GetName(
*module)
Part of the
.Similar to
but return the name encoded to 'utf-8'.
The returned buffer is only valid until the module is renamed or destroyed. Note that Python code may rename a module by setting its
attribute.
*PyModule_GetDef(
*module)
Part of the
.Return a pointer to the
struct from which the module was created, or NULL if the module wasn’t created from a definition.
On error, return NULL with an exception set. Use
to tell this case apart from a missing PyModuleDef.
*PyModule_GetFilenameObject(
*module)
Return value: New reference. Part of the
.Return the name of the file from which module was loaded using module’s
attribute. If this is not defined, or if it is not a string, raise
and return NULL; otherwise return a reference to a Unicode object.
Added in version 3.2.
constchar*PyModule_GetFilename(
*module)
Part of the
.Similar to
but return the filename encoded to ‘utf-8’.
The returned buffer is only valid until the module’s
attribute is reassigned or the module is destroyed.
Deprecated since version 3.2:
raises
on unencodable filenames, use
instead.
Module definition
Modules created using the C API are typically defined using an array of
structs, which provides a “description” of how a module should be created. See
for more information on slots in general.
Changed in version 3.15: Previously, a
struct was necessary to define modules. The older way of defining modules is still available: consult either the
section or earlier versions of this documentation if you plan to support earlier Python versions.
The slots array is usually used to define an extension module’s “main” module object (see
for details). It can also be used to
create extension modules dynamically
.
Unless specified otherwise, the same slot ID may not be repeated in an array of slots.
Metadata slots
Py_mod_name
Part of the
since version 3.15.
for the name of the new module, as a NUL-terminated UTF8-encoded constchar*.
Note that modules are typically created using a
, and when they are, the name from the spec will be used instead of Py_mod_name. However, it is still recommended to include this slot for introspection and debugging purposes.
Added in version 3.15: Use
instead to support previous versions.
Py_mod_doc
Part of the
since version 3.15.
for the docstring of the new module, as a NUL-terminated UTF8-encoded constchar*.
Usually it is set to a variable created with
.
Added in version 3.15: Use
instead to support previous versions.
Feature slots
Py_mod_abi
Part of the
since version 3.15.
whose value points to a
structure describing the ABI that the extension is using.
A suitable PyABIInfo variable can be defined using the
macro, as in:
PyABIInfo_VAR(abi_info);staticPySlotmymodule_slots[]={PySlot_DATA(Py_mod_abi,&abi_info),...};When creating a module, Python checks the value of this slot using
.
This slot is required, except for modules created from
.
Added in version 3.15.
Py_mod_multiple_interpreters
Part of the
since version 3.12.
whose value is one of:
Py_MOD_MULTIPLE_INTERPRETERS_NOT_SUPPORTED
The module does not support being imported in subinterpreters.
Py_MOD_MULTIPLE_INTERPRETERS_SUPPORTED
The module supports being imported in subinterpreters, but only when they share the main interpreter’s GIL. (See
.)
Py_MOD_PER_INTERPRETER_GIL_SUPPORTED
The module supports being imported in subinterpreters, even when they have their own GIL. (See
.)
This slot determines whether or not importing this module in a subinterpreter will fail.
If Py_mod_multiple_interpreters is not specified, the import machinery defaults to Py_MOD_MULTIPLE_INTERPRETERS_SUPPORTED.
For historical reasons, the values are declared as pointers (void*). When using
arrays, use
for Py_mod_multiple_interpreters:
PySlot_DATA(Py_mod_multiple_interpreters,Py_MOD_PER_INTERPRETER_GIL_SUPPORTED)Added in version 3.12.
Py_mod_gil
Part of the
since version 3.13.
whose value is one of:
Py_MOD_GIL_USED
The module depends on the presence of the global interpreter lock (GIL), and may access global state without synchronization.
Py_MOD_GIL_NOT_USED
The module is safe to run without an active GIL.
This slot is ignored by Python builds not configured with
. Otherwise, it determines whether or not importing this module will cause the GIL to be automatically enabled. See
for more detail.
If Py_mod_gil is not specified, the import machinery defaults to Py_MOD_GIL_USED.
For historical reasons, the values are declared as pointers (void*). When using
arrays, use
for Py_mod_gil:
PySlot_DATA(Py_mod_gil,Py_MOD_GIL_NOT_USED)Added in version 3.13.
Creation and initialization slots
Py_mod_create
Part of the
since version 3.5.
for a function that creates the module object itself. The function must have the signature:
*create_module(
*spec,
*def)
The function will be called with:
spec: a ModuleSpec-like object, meaning that any attributes defined for
importlib.machinery.ModuleSpec
have matching semantics. However, any of the attributes may be missing.
def: NULL, or the module definition if the module is created from one.
The function 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.
If Py_mod_create is not specified, the import machinery will create a normal module object using
. 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
. However, some slots may only be used with PyModule_Type instances; in particular:
,
(Py_mod_state_*),
.
Added in version 3.5.
Changed in version 3.15: The slots argument may be a ModuleSpec-like object, rather than a true
instance. Note that previous versions of CPython did not enforce this.
The def argument may now be NULL, since modules are not necessarily made from definitions.
Py_mod_exec
Part of the
since version 3.5.
for a function that will execute, or initialize, the module. This function does the equivalent to executing the code of a Python module: typically, it adds classes and constants to the module. The signature of the function is:
intexec_module(
*module)
See the
section for some useful functions to call.
For backwards compatibility, the
array may contain multiple Py_mod_exec slots; these are processed in the order they appear in the array. Elsewhere (that is, in arguments to
and in return values of PyModExport_<name>), repeating the slot is not allowed.
Added in version 3.5.
Changed in version 3.15: Repeated Py_mod_exec slots are disallowed, except in
.
Py_mod_methods
Part of the
since version 3.15.
for a table of module-level functions, as an array of
values suitable as the functions argument to
.
Like other slot IDs, a slots array may only contain one Py_mod_methods entry. To add functions from multiple
arrays, call
in the
function.
The table must be statically allocated (or otherwise guaranteed to outlive the module object).
Added in version 3.15: Use
instead to support previous versions.
Module state
Extension modules can have module state – a piece of memory that is allocated on module creation, and freed when the module object is deallocated. The module state is specified using
.
A typical use of module state is storing an exception type – or indeed any type object defined by the module –
Unlike the module’s Python attributes, Python code cannot replace or delete data stored in module state.
Keeping per-module information in attributes and module state, rather than in static globals, makes module objects isolated and safer for use in multiple sub-interpreters. It also helps Python do an orderly clean-up when it shuts down.
Extensions that keep references to Python objects as part of module state must implement
and
functions to avoid reference leaks.
To retrieve the state from a given module, use the following functions:
void*PyModule_GetState(
*module)
Part of the
.Return the “state” of the module, that is, a pointer to the block of memory allocated at module creation time, or NULL. See
.
On error, return NULL with an exception set. Use
to tell this case apart from missing module state.
intPyModule_GetStateSize(
*module,
*result)
Part of the
since version 3.15.Set *result to the size of module’s state, as specified using
(or
), and return 0.
On error, set *result to -1, and return -1 with an exception set.
Added in version 3.15.
Slots for defining module state
The following
are available for defining the module state.
Py_mod_state_size
Part of the
since version 3.15.
for the size of the module state, in bytes.
Setting the value to a non-negative value means that the module can be re-initialized and specifies the additional amount of memory it requires for its state.
See
for more details.
Use
to retrieve the size of a given module.
Added in version 3.15: Use
instead to support previous versions.
Py_mod_state_traverse
Part of the
since version 3.15.
for a traversal function to call during GC traversal of the module object.
The signature of the function, and meanings of the arguments, is similar as for
:
inttraverse_module_state(
*module,
visit, void*arg)
This function is not called if the module state was requested but is not allocated yet. This is the case immediately after the module is created and before the module is executed (
function). More precisely, this function is not called if the state size (
) is greater than 0 and the module state (as returned by
) is NULL.
Added in version 3.15: Use
instead to support previous versions.
Py_mod_state_clear
Part of the
since version 3.15.
for a clear function to call during GC clearing of the module object.
The signature of the function is:
intclear_module_state(
*module)
This function is not called if the module state was requested but is not allocated yet. This is the case immediately after the module is created and before the module is executed (
function). More precisely, this function is not called if the state size (
) is greater than 0 and the module state (as returned by
) is NULL.
Like
, this function is not always called before a module is deallocated. For example, when reference counting is enough to determine that an object is no longer used, the cyclic garbage collector is not involved and the
function is called directly.
Added in version 3.15: Use
instead to support previous versions.
Py_mod_state_free
Part of the
since version 3.15.
for a function to call during deallocation of the module object.
The signature of the function is:
intfree_module_state(
*module)
This function is not called if the module state was requested but is not allocated yet. This is the case immediately after the module is created and before the module is executed (
function). More precisely, this function is not called if the state size (
) is greater than 0 and the module state (as returned by
) is NULL.
Added in version 3.15: Use
instead to support previous versions.
Module token
Each module may have an associated token: a pointer-sized value intended to identify of the module state’s memory layout. This means that if you have a module object, but you are not sure if it “belongs” to your extension, you can check using code like this:
PyObject*module=<themoduleinquestion>void*module_token;if(PyModule_GetToken(module,&module_token)<0){returnNULL;}if(module_token!=your_token){PyErr_SetString(PyExc_ValueError,"unexpected module")returnNULL;}// This module's state has the expected memory layout; it's safe to caststructmy_statestate=(structmy_state*)PyModule_GetState(module)A module’s token – and the your_token value to use in the above code – is:
For modules created with
: the address of that PyModuleDef;
For modules defined with the
slot: the value of that slot;
For modules created from an PyModExport_*
: the slots array that the export hook returned (unless overridden with
).
Py_mod_token
Part of the
since version 3.15.
for the module token.
If you use this slot to set the module token (rather than rely on the default), you must ensure that:
The pointer outlives the class, so it’s not reused for something else while the class exists.
It “belongs” to the extension module where the class lives, so it will not clash with other extensions.
If the token points to a
struct, the module should behave as if it was created from that PyModuleDef. In particular, the module state must have matching layout and semantics.
Modules created from
always use the address of the PyModuleDef as the token. This means that Py_mod_token cannot be used in
.
Added in version 3.15.
intPyModule_GetToken(
*module, void**result)
Part of the
since version 3.15.Set *result to the module token for module and return 0.
On error, set *result to NULL, and return -1 with an exception set.
Added in version 3.15.
See also
.
Creating extension modules dynamically
The following functions may be used to create an extension module dynamically, rather than from an extension’s
.
*PyModule_FromSlotsAndSpec(const
*slots,
*spec)
Return value: New reference. Part of the
since version 3.15.Create a new module object, given an array of
and the
spec.
The slots argument must point to an array of
structures, terminated by an entry with slot ID of 0 (typically written as
). The array must include a
entry.
The spec argument may be any ModuleSpec-like object, as described in
documentation. Currently, the spec must have a name attribute.
On success, return the new module. On error, return NULL with an exception set.
Note that this does not process the module’s execution slot (
). Both PyModule_FromSlotsAndSpec() and
must be called to fully initialize a module. (See also
.)
Added in version 3.15.
intPyModule_Exec(
*module)
Part of the
since version 3.15.Execute the
slot(s) of module.
On success, return 0. On error, return -1 with an exception set.
For clarity: If module has no slots, for example if it uses
legacy single-phase initialization
, this function does nothing and returns 0.
Added in version 3.15.
Module definition struct
Traditionally, extension modules were defined using a module definition as the “description” of how a module should be created. Rather than using an array of
directly, the definition has dedicated members for most common functionality, and allows additional slots as an extension mechanism.
This way of defining modules is still available and there are no plans to remove it.
typePyModuleDef
Part of the
(see below).The module definition struct, which holds information needed to create a module object.
This structure must be statically allocated (or be otherwise guaranteed to be valid while any modules created from it exist). Usually, there is only one variable of this type for each extension module defined this way.
The struct, including all members, is part of the
for non-free-threaded builds (abi3). In the Stable ABI for free-threaded builds (abi3t), this struct is opaque, and unusable in practice; see
for a replacement.
m_base
Always initialize this member to
:
typePyModuleDef_Base
Part of the
(see below).The type of PyModuleDef.m_base.
The struct is part of the
for non-free-threaded builds (abi3). In the Stable ABI for Free-Threaded Builds (abi3t), this struct is opaque, and unusable in practice.
PyModuleDef_HEAD_INIT
The required initial value for PyModuleDef.m_base.
constchar*m_name
Corresponds to the
slot.
constchar*m_doc
These members correspond to the
slot. Setting this to NULL is equivalent to omitting the slot.
m_size
Corresponds to the
slot. Setting this to zero is equivalent to omitting the slot.
When using
legacy single-phase initialization
or when creating modules dynamically using
or
, m_size may be set to -1. This indicates that the module does not support sub-interpreters, because it has global state.
*m_methods
Corresponds to the
slot. Setting this to NULL is equivalent to omitting the slot.
*m_slots
An array of additional slots, terminated by a {0,NULL} entry. Note that the entries use the older
structure, rather than
.
If the array contains slots corresponding to
members, the values must match. For example, if you use
in m_slots,
must be set to the same pointer (not just an equal string).
Changed in version 3.5: Prior to version 3.5, this member was always set to NULL, and was defined as:
typePyModuleDef_Slot
Part of the
(including all members) since version 3.5.Older structure defining additional slots of a module.
Note that a PyModuleDef_Slot array may be included in a PySlot array using
, and vice versa using
.
Each PyModuleDef_Slot structure modslot is interpreted as the following
structure:
(PySlot){.sl_id=modslot.slot,.sl_flags=PySlot_INTPTR|sub_static,.sl_ptr=modslot.value}where sub_static is PySlot_STATIC if the slot requires the flag (such as for
), or if this flag is present on the “parent” Py_mod_slots slot (if any).
intslot
Corresponds to
.
void*value
Corresponds to
.
Added in version 3.5.
m_traverse
m_clear
m_free
These members correspond to the
,
, and
slots, respectively.
Setting these members to NULL is equivalent to omitting the corresponding slots.
Changed in version 3.9:
,
and
functions are no longer called before the module state is allocated.
PyModuleDef_Type
Part of the
since version 3.5.The type of PyModuleDef objects.
Py_mod_slots
Part of the
since version 3.15.
that works like
, except it specifies an array of
structures.
Added in version 3.15.
The following API can be used to create modules from a PyModuleDef struct:
*PyModule_Create(
*def)
Return value: New reference.Create a new module object, given the definition in def. This is a macro that calls
with module_api_version set to
, or to
if using the
.
*PyModule_Create2(
*def, intmodule_api_version)
Return value: New reference. Part of the
.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
is emitted.
Return NULL with an exception set on error.
This function does not support slots. The
member of def must be NULL.
Note
Most uses of this function should be using
instead; only use this if you are sure you need it.
*PyModule_FromDefAndSpec(
*def,
*spec)
Return value: New reference.This macro calls
with module_api_version set to
, or to
if using the
.
Added in version 3.5.
*PyModule_FromDefAndSpec2(
*def,
*spec, intmodule_api_version)
Return value: New reference. Part of the
since version 3.7.Create a new module object, given the definition in def and the ModuleSpec spec, assuming the API version module_api_version. If that version does not match the version of the running interpreter, a
is emitted.
Return NULL with an exception set on error.
Note that this does not process execution slots (
). Both PyModule_FromDefAndSpec and PyModule_ExecDef must be called to fully initialize a module.
Note
Most uses of this function should be using
instead; only use this if you are sure you need it.
Added in version 3.5.
intPyModule_ExecDef(
*module,
*def)
Part of the
since version 3.7.Process any execution slots (
) given in def.
Added in version 3.5.
since version 3.15: To run a module’s own execution slots, prefer
, which works on modules that were not created from a
structure.
PYTHON_API_VERSION
PYTHON_API_STRING
The C API version, as an integer (1013) and string ("1013"), respectively. Defined for backwards compatibility.
Currently, this constant is not updated in new Python versions, and is not useful for versioning. This may change in the future.
PYTHON_ABI_VERSION
PYTHON_ABI_STRING
Defined as 3 and "3", respectively, for backwards compatibility.
Currently, this constant is not updated in new Python versions, and is not useful for versioning. This may change in the future.
Support functions
The following functions are provided to help initialize a module object. They are intended for a module’s execution slot (
), the initialization function for legacy
, or code that creates modules dynamically.
intPyModule_AddObjectRef(
*module, constchar*name,
*value)
Part of the
since version 3.10.Add an object to module as name. This is a convenience function which can be used from the module’s initialization function.
On success, return 0. On error, raise an exception and return -1.
Example usage:
staticintadd_spam(PyObject*module,intvalue){PyObject*obj=PyLong_FromLong(value);if(obj==NULL){return-1;}intres=PyModule_AddObjectRef(module,"spam",obj);Py_DECREF(obj);returnres;}To be convenient, the function accepts NULLvalue with an exception set. In this case, return -1 and just leave the raised exception unchanged.
The example can also be written without checking explicitly if obj is NULL:
staticintadd_spam(PyObject*module,intvalue){PyObject*obj=PyLong_FromLong(value);intres=PyModule_AddObjectRef(module,"spam",obj);Py_XDECREF(obj);returnres;}Note that Py_XDECREF() should be used instead of Py_DECREF() in this case, since obj can be NULL.
The number of different name strings passed to this function should be kept small, usually by only using statically allocated strings as name. For names that aren’t known at compile time, prefer calling
and
directly. For more details, see
, which may be used internally to create a key object.
Added in version 3.10.
intPyModule_Add(
*module, constchar*name,
*value)
Part of the
since version 3.13.Similar to
, but “
” a reference to value (even on error). It can be called with a result of function that returns a new reference without bothering to check its result or even saving it to a variable.
Example usage:
if(PyModule_Add(module,"spam",PyBytes_FromString(value))<0){gotoerror;}Added in version 3.13.
intPyModule_AddObject(
*module, constchar*name,
*value)
Part of the
.Similar to
, but
a reference to value on success (if it returns 0).
The new
or
functions are recommended, since it is easy to introduce reference leaks by misusing the
function.
Note
Unlike other functions that steal references, PyModule_AddObject() only releases the reference to valueon success.
This means that its return value must be checked, and calling code must
value manually on error.
Example usage:
PyObject*obj=PyBytes_FromString(value);if(PyModule_AddObject(module,"spam",obj)<0){// If 'obj' is not NULL and PyModule_AddObject() failed,// 'obj' strong reference must be deleted with Py_XDECREF().// If 'obj' is NULL, Py_XDECREF() does nothing.Py_XDECREF(obj);gotoerror;}// PyModule_AddObject() stole a reference to obj:// Py_XDECREF(obj) is not needed here.intPyModule_AddIntConstant(
*module, constchar*name, longvalue)
Part of the
.Add an integer constant to module as name. This convenience function can be used from the module’s initialization function. Return -1 with an exception set on error, 0 on success.
This is a convenience function that calls
and
; see their documentation for details.
intPyModule_AddStringConstant(
*module, constchar*name, constchar*value)
Part of the
.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 with an exception set on error, 0 on success.
This is a convenience function that calls
and
; see their documentation for details.
PyModule_AddIntMacro(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 with an exception set on error, 0 on success.
PyModule_AddStringMacro(module, macro)
Add a string constant to module.
intPyModule_AddType(
*module,
*type)
Part of the
since version 3.10.Add a type object to module. The type object is finalized by calling internally
. The name of the type object is taken from the last component of
after dot. Return -1 with an exception set on error, 0 on success.
Added in version 3.9.
intPyModule_AddFunctions(
*module,
*functions)
Part of the
since version 3.7.Add the functions from the NULL terminated functions array to module. Refer to the
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 (such as when using
, PyModule_Create, or PyModule_FromDefAndSpec). Some module authors may prefer defining functions in multiple
arrays; in that case they should call this function directly.
The functions array must be statically allocated (or otherwise guaranteed to outlive the module object).
Added in version 3.5.
intPyModule_SetDocString(
*module, constchar*docstring)
Part of the
since version 3.7.Set the docstring for module to docstring. This function is called automatically when creating a module from PyModuleDef (such as when using
, PyModule_Create, or PyModule_FromDefAndSpec).
Return 0 on success. Return -1 with an exception set on error.
Added in version 3.5.
intPyUnstable_Module_SetGIL(
*module, void*gil)
This is
. It may change without warning in minor releases.
Indicate that module does or does not support running without the global interpreter lock (GIL), using one of the values from
. It must be called during module’s initialization function when using
Legacy single-phase initialization
. If this function is not called during module initialization, the import machinery assumes the module does not support running without the GIL. This function is only available in Python builds configured with
. Return -1 with an exception set on error, 0 on success.
Added in version 3.13.
Module lookup (single-phase initialization)
The legacy
initialization scheme creates singleton modules that can be looked up in the context of the current interpreter. This allows the module object to be retrieved later with only a reference to the module definition.
These functions will not work on modules created using multi-phase initialization, since multiple such modules can be created from a single definition.
*PyState_FindModule(
*def)
Return value: Borrowed reference. Part of the
.Returns the module object that was created from def for the current interpreter. This method requires that the module object has been attached to the interpreter state with
beforehand. In case the corresponding module object is not found or has not been attached to the interpreter state yet, it returns NULL.
intPyState_AddModule(
*module,
*def)
Part of the
since version 3.3.Attaches the module object passed to the function to the interpreter state. This allows the module object to be accessible via
.
Only effective on modules created using single-phase initialization.
Python calls PyState_AddModule automatically after importing a module that uses
, so it is unnecessary (but harmless) to call it from module initialization code. An explicit call is needed only if the module’s own init code subsequently calls PyState_FindModule. The function is mainly intended for implementing alternative import mechanisms (either by calling it directly, or by referring to its implementation for details of the required state updates).
If a module was attached previously using the same def, it is replaced by the new module.
The caller must have an
.
Return -1 with an exception set on error, 0 on success.
Added in version 3.3.
intPyState_RemoveModule(
*def)
Part of the
since version 3.3.Removes the module object created from def from the interpreter state. Return -1 with an exception set on error, 0 on success.
The caller must have an
.
Added in version 3.3.