Could "==" and "is" be merged? Same for "!=" and "is not"

[PIZZA-ALERT]

Currently, "==" and "!=" check for a value. Examples:

if var_name1 == 0
if var_name2 != ""
if var_name3 == var_name4

Also currently, "is" and "is not" check for a class. Examples:

if var_name1 is Node
if var_name2 is not String
if var_name3 is Array

Yet also currently, "!" and "not" are the same. Examples:
if !var_name1 is String
is the same as
if not var_name1 is String

However,
if var_name1 is not String
is not the same as
if var_name1 != String

Why?

Now, I'm sure there are very established rules in place within Python, etc. as to why this is the case. However, I'm not a coding expert, so I'd like to challenge that in Godot! I wanted to start this as a discussion first as it's potentially a big change.

Could this syntax be merged for the sake of accessibility and readability, as well as for any other reason you, the reader, may think of?

[TheDuriel]

You appear to be confused about the ! and not keywords:

the not and ! keywords, which are the same, invert a boolean. Specifically they turn true to false and false to true. No more, no less.

The ! found within != does not have anything to do with that. It doesn't invert the expression value itself. But changes the expression itself to check for false instead of true.

!true and not true are both false

!false and not false are both true

if (not (1 == 2)) == true:

This is the actual anatomy of an if statement. Note that the == true at the end is always implicit and doesn't have to be typed out. So as you can see, first 1 and 2 are compared, returning false, then the not not or ! keyword turns that into true, and then we check for whether or not the outcome of that, is true.

---

Beyond that, it is not possible to merge == and is, because they do different things. There are absolutely situations in which you might want to type the exact same comparison but with the other operator. And removing it would just... well. Break everything.

[PIZZA-ALERT]

No I don't believe that I'm confused about the true/false at all, but thanks for explaining it in case I was or anyone else is. All I'm confused on really is why "is" and "==" couldn't both have both value and class evaluation abilities simultaneously.

You absolutely don't need to go out of your way for me, but would you be able to give an example of a situation from your last point? I just personally haven't experienced a time where something would break on my end if I put "is" where "==" goes, or vice versa, for any reason other than GDScript doesn't allow it. From my perspective, typing both should work either way.

And again to be clear, this whole discussion is a suggestion to change GDScript to allow both in either situation, so despite the fact that currently they have different functions, I'm saying maybe they could have the same function in a future release.

[TheDuriel]

Your code example in your post, had them wrong.

And we can't merge value and type comparison because we need to be specific.

Merging results in a loss of functionality that can only be made up for by adding a new way to type the same thing.

How can I check if two script resources are different objects, when it will always check if they extend each other instead? Don't answer that. You'd have to specify with === or is.

[PIZZA-ALERT]

I'm not sure what is messed up in my post, but sorry about that if so.

Your last part finally made it click for me I think. Even though I think you effectively said the same thing a few times here and on Reddit, the way you worded it there made it make sense for me.

Perhaps what's confusing for me and possibly others who make this mistake, is the literal verbage in the script being "is." To me, "is" means IS. Like, it IS something. The code looks like it's saying "this IS that." However, truly "==" means it IS something, while "is" means it IS EXTENDING something or IS INSTANCING something. Just kinda weird.

[theraot]

if var_name1 is not String

Is not the same as

if var_name1 != String

Because

if var_name1 is String

Is not the same as

if var_name1 == String

The former (if var_name1 is String) is checking if var_name1 is a String, any String.

The latter (if var_name1 == String) is checking if var_name1 is the String type.

Be aware that in GDScript a variable can hold a tytpe.

For example, let us say I have a script "res://my_script.gd" like this:

class_name MyScript

If then do this in some other script:

	var my_variable = load("res://my_script.gd")
	if my_variable == MyScript:
		print("The types are the same")

	var instance = my_variable.new()
	if instance is MyScript:
		print("The instance is of the type")

	if instance != MyScript:
		print("The instance is not the same thing as its type")

	if my_variable == MyScript:
		print("The variable holds the type")

	if my_variable is not MyScript:
		print("The type of the type is not itself")

	if my_variable is Script:
		print("Actually the type is a Script")

	if instance is not Script:
		print("Oh, and the instance is not a Script")

I get all those print outs:

The types are the same
The instance is of the type
The instance is not the same thing as its type
The variable holds the type
The type of the type is not itself
Actually the type is a Script
Oh, and the instance is not a Script

We can imagine a world where GDScript would pick up kind of check to do based on the types (e.g. if one of the values is a type check if the other is a value of that type), however that would erode our ability to do the checks shown above.