Add expression evaluator to debugger (REPL)

[KoBeWi]

Supersedes #60134
Supersedes #76736
Closes godotengine/godot-proposals#4473

For now it's just rebased branch, putting it as draft until I clean it up and fix issues.

[Faless]

Looking good overall, see review comments.

As mentioned in the other PR, this feature should also be disabled in release build (and probably extracted as an EditorDebuggerPlugin), but we can do that in a separate PR.

[KoBeWi]

this feature should also be disabled in release build

This feature is a part of debugger. Does it even exist in release builds?

probably extracted as an EditorDebuggerPlugin

I can do that in a follow-up.

[Faless]

This feature is a part of debugger. Does it even exist in release builds?

Yes the debugger is not fully disabled in release builds, only parts of it (like live scene editing), it's historically always been like that, but of course this should be re-evaluated

[Faless]

LGTM

[akien-mga]

Looks great!

[Calinou]

Tested locally, the UI appears to be disabled regardless of whether the project is currently running:

I have a GDScript open in the script tab before running the project.

("Expression to evaluate" is a read-only LineEdit.)

[KoBeWi]

You can only evaluate when the game is breaked (at breakpoint, error etc.). Maybe this should be more obvious, but it can be improved later.

[akien-mga]

Maybe the LineEdit could have a centered message in this case that says "To evaluate expressions, the project must be running with the execution interrupted by a breakpoint or error."

[mathrick]

Maybe the LineEdit could have a centered message in this case that says "To evaluate expressions, the project must be running with the execution interrupted by a breakpoint or error."

Wording suggestion: "Expressions can only be evaluated when a running project is paused in the debugger"

[rohanrhu]

Thank you.

[akien-mga]

I forgot to say thanks when merging this, I had wrongly closed the tab /o\

Thanks to everyone involved in implementing this feature, @rohanrhu, @rxlecky and @KoBeWi!

[rxlecky]

Great stuff, it's amazing to see this feature finally implemented, after I was unable to do so. Thanks @rohanrhu ! ❤️

[GyuchanLim]

Hello, I've been using this feature on the Godot 4.4 dev 3 snapshot and I am loving this feature.
And I have a potential newbie question.

Is there a way to see the Object value of Display.dealer_total just like how you can with dealt_card

[KoBeWi]

You should be able to see it in the inspector when you click the object.

[Musclorman]

Google translate:
Hello. Why not copy the python interpreter?

French original text:
Bonjour. Pourquoi pas copier l'interpreteur python?

[KoBeWi]

Because it serves a different purpose. It's a tool for debugging a running project.

If you want a GDScript interpreter, you can use one available online, like https://gd.tumeo.space/