140 lines
4.1 KiB
ReStructuredText
140 lines
4.1 KiB
ReStructuredText
.. highlight:: c
|
|
|
|
.. _contextvarsobjects:
|
|
|
|
Context Variables Objects
|
|
-------------------------
|
|
|
|
.. _contextvarsobjects_pointertype_change:
|
|
.. versionchanged:: 3.7.1
|
|
|
|
.. note::
|
|
|
|
In Python 3.7.1 the signatures of all context variables
|
|
C APIs were **changed** to use :c:type:`PyObject` pointers instead
|
|
of :c:type:`PyContext`, :c:type:`PyContextVar`, and
|
|
:c:type:`PyContextToken`, e.g.::
|
|
|
|
// in 3.7.0:
|
|
PyContext *PyContext_New(void);
|
|
|
|
// in 3.7.1+:
|
|
PyObject *PyContext_New(void);
|
|
|
|
See :issue:`34762` for more details.
|
|
|
|
|
|
.. versionadded:: 3.7
|
|
|
|
This section details the public C API for the :mod:`contextvars` module.
|
|
|
|
.. c:type:: PyContext
|
|
|
|
The C structure used to represent a :class:`contextvars.Context`
|
|
object.
|
|
|
|
.. c:type:: PyContextVar
|
|
|
|
The C structure used to represent a :class:`contextvars.ContextVar`
|
|
object.
|
|
|
|
.. c:type:: PyContextToken
|
|
|
|
The C structure used to represent a :class:`contextvars.Token` object.
|
|
|
|
.. c:var:: PyTypeObject PyContext_Type
|
|
|
|
The type object representing the *context* type.
|
|
|
|
.. c:var:: PyTypeObject PyContextVar_Type
|
|
|
|
The type object representing the *context variable* type.
|
|
|
|
.. c:var:: PyTypeObject PyContextToken_Type
|
|
|
|
The type object representing the *context variable token* type.
|
|
|
|
|
|
Type-check macros:
|
|
|
|
.. c:function:: int PyContext_CheckExact(PyObject *o)
|
|
|
|
Return true if *o* is of type :c:data:`PyContext_Type`. *o* must not be
|
|
``NULL``. This function always succeeds.
|
|
|
|
.. c:function:: int PyContextVar_CheckExact(PyObject *o)
|
|
|
|
Return true if *o* is of type :c:data:`PyContextVar_Type`. *o* must not be
|
|
``NULL``. This function always succeeds.
|
|
|
|
.. c:function:: int PyContextToken_CheckExact(PyObject *o)
|
|
|
|
Return true if *o* is of type :c:data:`PyContextToken_Type`.
|
|
*o* must not be ``NULL``. This function always succeeds.
|
|
|
|
|
|
Context object management functions:
|
|
|
|
.. c:function:: PyObject *PyContext_New(void)
|
|
|
|
Create a new empty context object. Returns ``NULL`` if an error
|
|
has occurred.
|
|
|
|
.. c:function:: PyObject *PyContext_Copy(PyObject *ctx)
|
|
|
|
Create a shallow copy of the passed *ctx* context object.
|
|
Returns ``NULL`` if an error has occurred.
|
|
|
|
.. c:function:: PyObject *PyContext_CopyCurrent(void)
|
|
|
|
Create a shallow copy of the current thread context.
|
|
Returns ``NULL`` if an error has occurred.
|
|
|
|
.. c:function:: int PyContext_Enter(PyObject *ctx)
|
|
|
|
Set *ctx* as the current context for the current thread.
|
|
Returns ``0`` on success, and ``-1`` on error.
|
|
|
|
.. c:function:: int PyContext_Exit(PyObject *ctx)
|
|
|
|
Deactivate the *ctx* context and restore the previous context as the
|
|
current context for the current thread. Returns ``0`` on success,
|
|
and ``-1`` on error.
|
|
|
|
|
|
Context variable functions:
|
|
|
|
.. c:function:: PyObject *PyContextVar_New(const char *name, PyObject *def)
|
|
|
|
Create a new ``ContextVar`` object. The *name* parameter is used
|
|
for introspection and debug purposes. The *def* parameter may optionally
|
|
specify the default value for the context variable. If an error has
|
|
occurred, this function returns ``NULL``.
|
|
|
|
.. c:function:: int PyContextVar_Get(PyObject *var, PyObject *default_value, PyObject **value)
|
|
|
|
Get the value of a context variable. Returns ``-1`` if an error has
|
|
occurred during lookup, and ``0`` if no error occurred, whether or not
|
|
a value was found.
|
|
|
|
If the context variable was found, *value* will be a pointer to it.
|
|
If the context variable was *not* found, *value* will point to:
|
|
|
|
- *default_value*, if not ``NULL``;
|
|
- the default value of *var*, if not ``NULL``;
|
|
- ``NULL``
|
|
|
|
If the value was found, the function will create a new reference to it.
|
|
|
|
.. c:function:: PyObject *PyContextVar_Set(PyObject *var, PyObject *value)
|
|
|
|
Set the value of *var* to *value* in the current context. Returns a
|
|
pointer to a :c:type:`PyObject` object, or ``NULL`` if an error
|
|
has occurred.
|
|
|
|
.. c:function:: int PyContextVar_Reset(PyObject *var, PyObject *token)
|
|
|
|
Reset the state of the *var* context variable to that it was in before
|
|
:c:func:`PyContextVar_Set` that returned the *token* was called.
|
|
This function returns ``0`` on success and ``-1`` on error.
|