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.. highlight:: c
Curses C API
------------
:mod:`curses` exposes a small C interface for extension modules.
Consumers must include the header file :file:`py_curses.h` (which is not
included by default by :file:`Python.h`) and :c:func:`import_curses` must
be invoked, usually as part of the module initialisation function, to populate
:c:var:`PyCurses_API`.
.. warning::
Neither the C API nor the pure Python :mod:`curses` module are compatible
with subinterpreters.
.. c:macro:: import_curses()
Import the curses C API. The macro does not need a semi-colon to be called.
On success, populate the :c:var:`PyCurses_API` pointer.
On failure, set :c:var:`PyCurses_API` to NULL and set an exception.
The caller must check if an error occurred via :c:func:`PyErr_Occurred`:
.. code-block::
import_curses(); // semi-colon is optional but recommended
if (PyErr_Occurred()) { /* cleanup */ }
.. c:var:: void **PyCurses_API
Dynamically allocated object containing the curses C API.
This variable is only available once :c:macro:`import_curses` succeeds.
``PyCurses_API[0]`` corresponds to :c:data:`PyCursesWindow_Type`.
``PyCurses_API[1]``, ``PyCurses_API[2]``, and ``PyCurses_API[3]``
are pointers to predicate functions of type ``int (*)(void)``.
When called, these predicates return whether :func:`curses.setupterm`,
:func:`curses.initscr`, and :func:`curses.start_color` have been called
respectively.
See also the convenience macros :c:macro:`PyCursesSetupTermCalled`,
:c:macro:`PyCursesInitialised`, and :c:macro:`PyCursesInitialisedColor`.
.. note::
The number of entries in this structure is subject to changes.
Consider using :c:macro:`PyCurses_API_pointers` to check if
new fields are available or not.
.. c:macro:: PyCurses_API_pointers
The number of accessible fields (``4``) in :c:var:`PyCurses_API`.
This number is incremented whenever new fields are added.
.. c:var:: PyTypeObject PyCursesWindow_Type
The :ref:`heap type <heap-types>` corresponding to :class:`curses.window`.
.. c:function:: int PyCursesWindow_Check(PyObject *op)
Return true if *op* is a :class:`curses.window` instance, false otherwise.
The following macros are convenience macros expanding into C statements.
In particular, they can only be used as ``macro;`` or ``macro``, but not
``macro()`` or ``macro();``.
.. c:macro:: PyCursesSetupTermCalled
Macro checking if :func:`curses.setupterm` has been called.
The macro expansion is roughly equivalent to:
.. code-block::
{
typedef int (*predicate_t)(void);
predicate_t was_setupterm_called = (predicate_t)PyCurses_API[1];
if (!was_setupterm_called()) {
return NULL;
}
}
.. c:macro:: PyCursesInitialised
Macro checking if :func:`curses.initscr` has been called.
The macro expansion is roughly equivalent to:
.. code-block::
{
typedef int (*predicate_t)(void);
predicate_t was_initscr_called = (predicate_t)PyCurses_API[2];
if (!was_initscr_called()) {
return NULL;
}
}
.. c:macro:: PyCursesInitialisedColor
Macro checking if :func:`curses.start_color` has been called.
The macro expansion is roughly equivalent to:
.. code-block::
{
typedef int (*predicate_t)(void);
predicate_t was_start_color_called = (predicate_t)PyCurses_API[3];
if (!was_start_color_called()) {
return NULL;
}
}
Internal data
-------------
The following objects are exposed by the C API but should be considered
internal-only.
.. c:macro:: PyCurses_CAPSULE_NAME
Name of the curses capsule to pass to :c:func:`PyCapsule_Import`.
Internal usage only. Use :c:macro:`import_curses` instead.
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