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by thaumasiotes 1753 days ago
> In any other scripting language I've worked on you can do some test on a reference to see if its null or doesn't exist.

Except - and this is called out in the github thread - the reference is not null and does exist. The check is working correctly.

The problem lies in the fact that what you want to check for is "is the object I originally pointed to still around?", but instead of doing that, you're checking "is the thing I'm pointing to currently a valid object?".

1 comments

Yes, but read further, there is no method to test whether the object I pointed to still exists. You have to listen for a signal that the object is leaving the scene and manually clear your reference.
https://docs.godotengine.org/en/stable/classes/class_%40gdsc...

I'm making a complex Godot game.

'is_instance_valid' does what you are describing.

Only in Debug builds. If you rely on it in a release build you will crash.

https://github.com/godotengine/godot-proposals/issues/1589 https://github.com/godotengine/godot/issues/41179

Reduz doesn't want the fix in release builds because the will be slower!

I don't understand. That's not what that PR says. That PR is about using == null. It offers no substantial information about is_instance_valid.
Apologies, you might need to do some digging and research on your own.

On Oct 2 @RandomShaper said "is_instance_valid() was made thread-safe, but it's still not something you can trust. An object allocated at the same address as a freed one will report a false positive. That's, of course, considering that what you want to check is that your variable is still pointing to the object you assigned, and not to just some object, which I think is the case.

@reduz respoinded with "Ah that may be still the case of 3.2, but in 4.0 this function is 100% trustworthy"

> there is no method to test whether the object I pointed to still exists

There probably is such a method, but you'd have to invoke it on the object, not on some other unrelated object.