GameMaker Foreach v3.0.1

GameMaker 2.3+

A foreach loop for arrays, lists, maps, structs, grids, strings and number ranges.

This foreach was made using macros so the variable scope is the same as in a regular for loop (because it is just a glorified for loop) and so you don't have to pass variables like arguments. You can access them inside of the loop directly.

Reserved keywords: foreach, foreach_rev, into, exec, as_list, as_grid, as_map, fe, fe_break, fe_continue, fe_return, global._FE_*

Changes

[v3.0.1] Renamed invar to into
It makes slightly more sense because you're passing data into the output variable

[v3.0.0] A complete refractor
+ managed to speed it up by about 40%
+ no more warnings
+ much cleaner code and macros
- DATA and VAR had to switch places. Now you first feed it data and then give it an output variable name

Syntax

foreach <data> into <var> exec

reversed loop:
foreach_rev <data> into <var> exec

• <var> - an unused variable name to use
• <data> - any supported data
  Only data that dont use keys as indexes can be reversed

DS datatypes require a specification:

foreach <some_ds_map> as_map into v exec
foreach <some_ds_list> as_list into v exec
foreach <some_ds_grid> as_grid into v exec

The macro variable fe contains these variables of the current loop body:

• index fe.i for array, list, grid, number range, string
• key fe.key for map, struct
• position fe.xpos, fe.ypos for grid
• write function fe.set(val) for anything but string and number range since those aren't references

To return from a function from within the loop use fe_return(val, [depth=1]);
To break the loop use fe_break;
To continue the loop use fe_continue;

While using fe_return you need to pay attention how "deep" the return is. If fe_return is called in a nested fe loop you have to specify how many fe loops to break using the depth parameter otherwise the stack doesn't get cleared correctly and it will cause unpredictable behaviour. (tbh I wouldn't return from within fe loops at all)

Still a one-liner

foreach xxx into v1 exec
  foreach xxx into v2 exec
    foreach xxx into v3 exec
      ...

Examples

var st = {
  one: 1,
  two: 2
};

foreach st into v exec {
  show_debug_message(fe.key + ": " + string(v));
}

var arr = [1,2,3,4,5,6];

foreach_rev arr into v exec {
  show_debug_message(string(fe.i) + ": " + string(v));
}

var map = ds_map_create();
ds_map_add(map, "one", 1);
ds_map_add(map, "two", 2);

foreach map as_map into v exec {
  show_debug_message(fe.key + ": " + string(v));
}

Range

• 1 param: from = 0, to = p1, step = 1
• 2 params: from = p1, to = p2, step = 1
• 3 params: from = p1, to = p2, step = p3

foreach 5 into v exec
  show_debug_message(v);

foreach -5, 5 into v exec
  show_debug_message(v);

foreach -5, 5, 0.5 into v exec
  show_debug_message(v);