Overriding functions

MY-BASIC supports overriding functions for prototype and referenced usertype.

Class instance

It's accepted to override functions of: TYPE, VAL, LEN, GET, SET; PUSH, POP, BACK, INSERT, SORT, EXISTS, INDEX_OF, REMOVE, CLEAR, ITERATOR, MOVE_NEXT. Define a member function with an underline (_) prefix to redirect execution to it. For example _LEN for overridding LEN, _PUSH for overridding PUSH, and so on. Overridden member functions accept any type and count of arguments, and could return any type of result.

Referenced usertype

Use mb_override_value to override built-in functions for referenced usertype.

Use MB_MF_FUNC to override generic functions including: TYPE, VAL, LEN, GET, SET.

Use MB_MF_COLL to override collection functions including: PUSH, POP, BACK, INSERT, SORT, EXISTS, INDEX_OF, REMOVE, CLEAR, ITERATOR, MOVE_NEXT.

The function to override with must be a pointer of mb_meta_status_e (* mb_meta_func_t)(struct mb_interpreter_t*, void**, const char*). Which returns MB_MS_NONE if the overridden function hadn't processed it, MB_MS_DONE of processing done; the return value can be bitwise OR MB_MS_RETURNED if the overridden function already pushed the return value to the interpreter.

Besides, it's possible to apply the CLONE statement to a referenced usertype to clone it, it may return nil if it's non-clonable. You don't need to write extra code to use this.

Others

Read the Overriding operators page to get information about overriding meta operators.