Can't compare arrays by reference

[rokasv]

Godot 3.1.1

I want to compare the arrays for uniqueness. I can't do it using array comparison.

var test = [1, 2]
var test2 = test
var test3 = [1, 2]
print(test == test)
print(test == test2)
print(test == test3)

The output is:

True 
True 
True

I expect:

True 
True
False

I want to be able to tell the difference between test2 and test3 as appending new values to test2 will not have them appended to test3.

i.e.

var test = [1, 2]
var test3 = [1, 2]
print(test == test3)
test3.append(4)
print(test == test3)

The output is:

True 
False

I need a way to compare the arrays by reference. There is no way to do it (?).
In other words, how do I get the pre-"fix" #1485 results?

[charliewhitfield]

I would like a solution to this problem too. Note that dictionaries act "correctly" (imho):

print({a=1} == {a=1})
print([1] == [1])

prints...

False
True

I'd much prefer to see arrays work as dictionaries. Otherwise, we need some way to test whether two arrays are different arrays, as stated by OP.

[tygree]

I'll look into this. Would you like this to be a change to the "==" operator or should an additional function be added to compare two arrays by reference?

[charliewhitfield]

I think arrays should work like dictionaries and objects, where "==" tests identity not content. I believe we are currently lacking any way to do an identity test for arrays.

I can certainly see the convenience value of one or more array (& dictionary) functions that compare content. But these should not be "==".

Edit: My need for a way to test array identity is in this procedural save/load system (submitted to Godot Asset Library a few days ago). Presently, we have to work with the warning: "A single array persisted in two places will become two on load". If I could test array identity, then I could remove that warning.

[charliewhitfield]

I opened a feature request to ask for ability to test array identity, whether it be == or some other way. If you need this functionality, or have an opinion on implementation, please go over there to comment.

[akien-mga]

Superseded by godotengine/godot-proposals#874.