In-Game: string() and show_debug_message() should add support for {{ and }} to escape the brace characters

[gm-bug-reporter]

Description

When string is applied at the runtime, all numbers between curly braces are replaced with corresponding arguments (unless no corresponding argument is found, then they're passed as-is). There seems to be no special behaviour that would allow escaping the braces by doubling them like in C#.

However, if a string call is resolvable at compile time, the double curly braces are treated as non-placeholder single braces, the way C# runs its string.Format.

Whether the intended behaviour is to allow escaping double curly braces or just replacing patterns as-is, this is an inconsistency between equivalent runtime and compile time behaviours. I don't mind either way (although I prefer having an option to escape than not), as long as runtime and compiler agree.

Steps To Reproduce

Create an empty project and a script with a following code:

var _zero = "zero";
var _one = "one";

show_debug_message(string("This is some {{0}} and this is {1}", _zero, _one));
show_debug_message(string("This is some {{0}} and this is {1}", "zero", "one"));

The result is:

This is some {zero} and this is one
This is some {0} and this is one

That's presumably because C# escapes double-braces as non-placeholder single braces, while runtime simply searches and replaces "digits between braces" pattern.

Which version of GameMaker are you reporting this issue for?

IDE v2024.1100.0.700 Runtime v2024.1100.0.718

Which operating system(s) are you seeing the problem on?

Windows 10.0.19045.0

Which platform(s) are you seeing the problem on?

HTML5, Windows

a7695c1c-4a00-4b58-a231-9667d33eaf28

[YYBartT]

Added a paragraph on the string() manual page that mentions when curly braces in a format string are not replaced and how they can be escaped.

[mgeddesGM]

verified as of IDE v2024.1300.0.719 Runtime v2024.1300.0.731

[YYDan]

Note that the same change was made for show_debug_message() also, so I have added this to the title here.