# Curses C API

`curses` exposes a small C interface for extension modules. Consumers must include the header file `py_curses.h` (which is not included by default by `Python.h`) and `import_curses()` must be invoked, usually as part of the module initialisation function, to populate `PyCurses_API`.

Warning

Neither the C API nor the pure Python `curses` module are compatible with subinterpreters.

import_curses()

  Import the curses C API. The macro does not need a semi-colon to be called.

  On success, populate the `PyCurses_API` pointer.

  On failure, set `PyCurses_API` to NULL and set an exception. The caller must check if an error occurred via `PyErr_Occurred()`:

      import_curses();  // semi-colon is optional but recommended
      if (PyErr_Occurred()) { /* cleanup */ }

void **PyCurses_API

  Dynamically allocated object containing the curses C API. This variable is only available once `import_curses` succeeds.

  `PyCurses_API[0]` corresponds to `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 `curses.setupterm()`, `curses.initscr()`, and `curses.start_color()` have been called respectively.

  See also the convenience macros `PyCursesSetupTermCalled`, `PyCursesInitialised`, and `PyCursesInitialisedColor`.

  Note

  The number of entries in this structure is subject to changes. Consider using `PyCurses_API_pointers` to check if new fields are available or not.

PyCurses_API_pointers

  The number of accessible fields (`4`) in `PyCurses_API`. This number is incremented whenever new fields are added.

PyTypeObject PyCursesWindow_Type

  The heap type corresponding to `curses.window`.

int PyCursesWindow_Check(PyObject *op)

  Return true if op is a `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();`.

PyCursesSetupTermCalled

  Macro checking if `curses.setupterm()` has been called.

  The macro expansion is roughly equivalent to:

      {
          typedef int (*predicate_t)(void);
          predicate_t was_setupterm_called = (predicate_t)PyCurses_API[1];
          if (!was_setupterm_called()) {
              return NULL;
          }
      }

PyCursesInitialised

  Macro checking if `curses.initscr()` has been called.

  The macro expansion is roughly equivalent to:

      {
          typedef int (*predicate_t)(void);
          predicate_t was_initscr_called = (predicate_t)PyCurses_API[2];
          if (!was_initscr_called()) {
              return NULL;
          }
      }

PyCursesInitialisedColor

  Macro checking if `curses.start_color()` has been called.

  The macro expansion is roughly equivalent to:

      {
          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.

PyCurses_CAPSULE_NAME

  Name of the curses capsule to pass to `PyCapsule_Import()`.

  Internal usage only. Use `import_curses` instead.