Defer execution of a block until another block is complete.

scr_defer.gml

/* Deferred Exeuction of Code
 * --------------------------
 * Kat @Katsaii
 */

#macro DEFER for (;; {
        
#macro UNTIL ; break; })

This works similar to defer in languages such as Go or Zig. Execution of the block between the macros DEFER and UNTIL is deferred until the execution of the block after UNTIL.

Destroying a list after three elements are added

var list = ds_list_create();
DEFER {
  ds_list_destroy(list);
} UNTIL {
  ds_list_add(list, 1);
  ds_list_add(list, 2);
  ds_list_add(list, 3);
}

Closing a text file after its content is read

var file = file_open_text("test.txt");
var msg = "";
DEFER file_close(file) UNTIL {
  while (!file_text_eof(file)) {
    msg += file_text_readln(file);
  }
}