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Sure, there are easy workarounds, but the issues are unexpected and secret (and now only in release). In any other scripting language I've worked on you can do

Sure, there are easy workarounds, but the issues are unexpected and secret (and now only in release). 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. In Godot you have to listen for the object reference leaving the scene. I can guarantee this is not an issue in Unity where a object that has been removed from the scene is null.

kevingadd 5y ago
As it happens, Unity has its own version of this problem, where it pretends that a non-null dangling reference is a null-reference: https://jacx.net/2015/11/20/dont-use-equals-null-on-unity-objects.html https://jacx.net/2015/11/20/dont-use-equals-null-on-unity-ob...
- jay_kyburz 5y ago
  That is not the same at all. The equivalent would be that your reference is pointing to some other object in the scene.
thaumasiotes 5y 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?".
- jay_kyburz 5y ago
  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.
  - thaumasiotes 5y ago
    > 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.
  - nightowl_games 5y ago
    https://docs.godotengine.org/en/stable/classes/class_%40gdscript.html#class-gdscript-method-is-instance-valid https://docs.godotengine.org/en/stable/classes/class_%40gdsc... I'm making a complex Godot game. 'is_instance_valid' does what you are describing.
    - jay_kyburz 5y ago
      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-proposals/issues/1589 https://github.com/godotengine/godot/issues/41179 https://github.com/godotengine/godot/issues/41179 Reduz doesn't want the fix in release builds because the will be slower!
      - nightowl_games 5y ago
        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.
        jay_kyburz 5y ago
        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"

kevingadd 5y ago

As it happens, Unity has its own version of this problem, where it pretends that a non-null dangling reference is a null-reference: https://jacx.net/2015/11/20/dont-use-equals-null-on-unity-objects.html https://jacx.net/2015/11/20/dont-use-equals-null-on-unity-ob...

jay_kyburz 5y ago
That is not the same at all. The equivalent would be that your reference is pointing to some other object in the scene.

thaumasiotes 5y 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?".

jay_kyburz 5y ago
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.
- thaumasiotes 5y ago
  > 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.
- nightowl_games 5y ago
  https://docs.godotengine.org/en/stable/classes/class_%40gdscript.html#class-gdscript-method-is-instance-valid https://docs.godotengine.org/en/stable/classes/class_%40gdsc... I'm making a complex Godot game. 'is_instance_valid' does what you are describing.
  - jay_kyburz 5y ago
    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-proposals/issues/1589 https://github.com/godotengine/godot/issues/41179 https://github.com/godotengine/godot/issues/41179 Reduz doesn't want the fix in release builds because the will be slower!
    - nightowl_games 5y ago
      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.
      - jay_kyburz 5y ago
        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"