Add curses key-management functions define_key(), key_defined() and keyok()

[serhiy-storchaka]

Feature or enhancement

The :mod:curses module does not expose the ncurses key-management extensions define_key(), key_defined() and keyok().

These let an application manage how curses recognizes control strings as keycodes, beyond the predefined terminfo keys and the all-or-nothing :meth:curses.window.keypad.

• define_key(definition, keycode) binds the control string definition to keycode. If definition is None the binding for keycode is removed; if keycode is zero or negative the binding for definition is removed.
• key_defined(definition) returns the keycode bound to definition, 0 if none is, or -1 if definition is ambiguous.
• keyok(keycode, enable) enables or disables recognition of a single keycode, a finer-grained alternative to :meth:curses.window.keypad.

Proposed API:

• curses.define_key(definition, keycode)
• curses.key_defined(definition) -> int
• curses.keyok(keycode, enable)

These are ncurses extensions, available when built against an ncurses with NCURSES_EXT_FUNCS.

Linked PRs

• gh-152334: Add curses key-management functions #152338