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| 1 | +.. highlightlang:: c |
| 2 | + |
| 3 | +.. _contextvarsobjects: |
| 4 | + |
| 5 | +Context Variables Objects |
| 6 | +------------------------- |
| 7 | + |
| 8 | +.. versionadded:: 3.7 |
| 9 | + |
| 10 | +This section details the public C API for the :mod:`contextvars` module. |
| 11 | + |
| 12 | +.. c:type:: PyContext |
| 13 | +
|
| 14 | + The C structure used to represent a :class:`contextvars.Context` |
| 15 | + object. |
| 16 | + |
| 17 | +.. c:type:: PyContextVar |
| 18 | +
|
| 19 | + The C structure used to represent a :class:`contextvars.ContextVar` |
| 20 | + object. |
| 21 | + |
| 22 | +.. c:type:: PyContextToken |
| 23 | +
|
| 24 | + The C structure used to represent a :class:`contextvars.Token` object. |
| 25 | + |
| 26 | +.. c:var:: PyTypeObject PyContext_Type |
| 27 | +
|
| 28 | + The type object representing the *context* type. |
| 29 | + |
| 30 | +.. c:var:: PyTypeObject PyContextVar_Type |
| 31 | +
|
| 32 | + The type object representing the *context variable* type. |
| 33 | + |
| 34 | +.. c:var:: PyTypeObject PyContextToken_Type |
| 35 | +
|
| 36 | + The type object representing the *context variable token* type. |
| 37 | + |
| 38 | + |
| 39 | +Type-check macros: |
| 40 | + |
| 41 | +.. c:function:: int PyContext_CheckExact(PyObject *o) |
| 42 | +
|
| 43 | + Return true if *o* is of type :c:data:`PyContext_Type`. *o* must not be |
| 44 | + *NULL*. This function always succeeds. |
| 45 | +
|
| 46 | +.. c:function:: int PyContextVar_CheckExact(PyObject *o) |
| 47 | +
|
| 48 | + Return true if *o* is of type :c:data:`PyContextVar_Type`. *o* must not be |
| 49 | + *NULL*. This function always succeeds. |
| 50 | +
|
| 51 | +.. c:function:: int PyContextToken_CheckExact(PyObject *o) |
| 52 | +
|
| 53 | + Return true if *o* is of type :c:data:`PyContextToken_Type`. |
| 54 | + *o* must not be *NULL*. This function always succeeds. |
| 55 | +
|
| 56 | +
|
| 57 | +Context object management functions: |
| 58 | +
|
| 59 | +.. c:function:: PyContext *PyContext_New(void) |
| 60 | +
|
| 61 | + Create a new empty context object. Returns ``NULL`` if an error |
| 62 | + has occurred. |
| 63 | +
|
| 64 | +.. c:function:: PyContext *PyContext_Copy(PyContext *ctx) |
| 65 | +
|
| 66 | + Create a shallow copy of the passed *ctx* context object. |
| 67 | + Returns ``NULL`` if an error has occurred. |
| 68 | +
|
| 69 | +.. c:function:: PyContext *PyContext_CopyCurrent(void) |
| 70 | +
|
| 71 | + Create a shallow copy of the current thread context. |
| 72 | + Returns ``NULL`` if an error has occurred. |
| 73 | +
|
| 74 | +.. c:function:: int PyContext_Enter(PyContext *ctx) |
| 75 | +
|
| 76 | + Set *ctx* as the current context for the current thread. |
| 77 | + Returns ``0`` on success, and ``-1`` on error. |
| 78 | +
|
| 79 | +.. c:function:: int PyContext_Exit(PyContext *ctx) |
| 80 | +
|
| 81 | + Deactivate the *ctx* context and restore the previous context as the |
| 82 | + current context for the current thread. Returns ``0`` on success, |
| 83 | + and ``-1`` on error. |
| 84 | +
|
| 85 | +.. c:function:: int PyContext_ClearFreeList() |
| 86 | +
|
| 87 | + Clear the context variable free list. Return the total number of |
| 88 | + freed items. This function always succeeds. |
| 89 | +
|
| 90 | +
|
| 91 | +Context variable functions: |
| 92 | +
|
| 93 | +.. c:function:: PyContextVar *PyContextVar_New(const char *name, PyObject *def) |
| 94 | +
|
| 95 | + Create a new ``ContextVar`` object. The *name* parameter is used |
| 96 | + for introspection and debug purposes. The *def* parameter may optionally |
| 97 | + specify the default value for the context variable. If an error has |
| 98 | + occurred, this function returns ``NULL``. |
| 99 | +
|
| 100 | +.. c:function:: int PyContextVar_Get(PyContextVar *var, PyObject *default_value, PyObject **value) |
| 101 | +
|
| 102 | + Get the value of a context variable. Returns ``-1`` if an error has |
| 103 | + occurred during lookup, and ``0`` if no error occurred, whether or not |
| 104 | + a value was found. |
| 105 | +
|
| 106 | + If the context variable was found, *value* will be a pointer to it. |
| 107 | + If the context variable was *not* found, *value* will point to: |
| 108 | +
|
| 109 | + - *default_value*, if not ``NULL``; |
| 110 | + - the default value of *var*, if not ``NULL``; |
| 111 | + - ``NULL`` |
| 112 | +
|
| 113 | + If the value was found, the function will create a new reference to it. |
| 114 | +
|
| 115 | +.. c:function:: PyContextToken *PyContextVar_Set(PyContextVar *var, PyObject *value) |
| 116 | +
|
| 117 | + Set the value of *var* to *value* in the current context. Returns a |
| 118 | + pointer to a :c:type:`PyContextToken` object, or ``NULL`` if an error |
| 119 | + has occurred. |
| 120 | +
|
| 121 | +.. c:function:: int PyContextVar_Reset(PyContextVar *var, PyContextToken *token) |
| 122 | +
|
| 123 | + Reset the state of the *var* context variable to that it was in before |
| 124 | + :c:func:`PyContextVar_Set` that returned the *token* was called. |
| 125 | + This function returns ``0`` on success and ``-1`` on error. |
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