Add a python-like enumerate option for iterators

[MathiasBaumgartinger]

Describe the project you are working on

irrelevant

Describe the problem or limitation you are having in your project

Especially for for each loops it is quite cumbersome to always index the container

var array: Array

for i in range(array.size()):
   ... array[i] ... 

or to always add an additional variable:

var array: Array
var count := 0
for element in array:
  ...
  count += 1

However an enumerate does have numerous additional use cases.

Describe the feature / enhancement and how it helps to overcome the problem or limitation

for each loops with index produce worse readable and/or additional unnecessary code lines, which could be easily avoided.

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

Just like in python a:

for i, element in enumerate(array):
  ...

would do the trick.

If this enhancement will not be used often, can it be worked around with a few lines of script?

I think i can confidently assume this would be used a lot.

Is there a reason why this should be core and not an add-on in the asset library?

Needs to be done at core level (to my knowledge it would even require a slight rewrite of "iteration" code base).

[Calinou]

for i in range(array.size()):

Can be shortened to:

for i in array.size():

This is also slightly faster in terms of run-time performance.

[Mickeon]

I am to assume the proposed implementation (with the Array method) would require it returning tuples, which Godot doesn't have, and I'm not sure it will anytime soon.

One other way to go about though, would be to be able to define two variables in the for loop, separated by a comma. One is inferred to be the index, and the other is the value. There was something similar suggested for Dictionaries (which would heavily benefit from this), but I do not have the proposal at hand.

[Zireael07]

Godot can return lists though, and I often return lists of [x.y] :P

[nlupugla]

I like the idea in principle, but adding new global scope methods like this technically breaks compatibility. That said, changing the syntax to array.enumerate() would solve this issue.

The bigger problem is that GDScript does not yet support multiple assignment with a line like for i, element in array.enumerate.

[MathiasBaumgartinger]

I am to assume the proposed implementation (with the Array method) would require it returning tuples, which Godot doesn't have, and I'm not sure it will anytime soon.

One other way to go about though, would be to be able to define two variables in the for loop, separated by a comma. One is inferred to be the index, and the other is the value. There was something similar suggested for Dictionaries (which would heavily benefit from this), but I do not have the proposal at hand.

I suppose you are talking about issue #1965

[PinkSerenity]

I am to assume the proposed implementation (with the Array method) would require it returning tuples, which Godot doesn't have, and I'm not sure it will anytime soon.

#2135 is about array unpacking, which would work as well.