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Bind event not compiling in blueprints


I a new to Unreal development. I'm using blueprints for my AI and I hope you can point me in the right direction for my problem.

I work with an AIPerception Component. When I bind a custom event to the OnTargetPerceptionUpdated event dispatcher -> it compiles. When I bind a custom event to the OnTargetUpdated event dispatcher -> it doesn't compile and gives me the message "Event signature error. Function not compatible".

Is this a bug in the engine ? Or is there a concept I don't get ?

ue version : 4.10.3 on windows

alt text

Product Version: UE 4.10
ue4_bp_compile.png (109.8 kB)
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asked Feb 21 '16 at 03:23 PM in Blueprint Scripting

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avatar image Shadowriver Feb 21 '16 at 04:37 PM

What type of array argument is?

avatar image Benlenem Feb 21 '16 at 04:38 PM

It is an array of Actor.

It is super easy to reproduce : I created the custom event with a simple drag and drop from the "Bind Event to OnPerceptionUpdated" box.

avatar image KieranChandler Mar 02 '16 at 08:26 PM

I am getting this too, except the parameter is an array of uclass pointers. my delegate declaration: https://gyazo.com/a6ec9e8273fb4d97d431d6994eb8b67d

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1 answer: sort voted first

I believe the problem here is blueprints use references, so the fix would be to change the delegate parameter type from




However, this introduces another error, because delegate parameters must be const. again, there is a simple fix for this:

 const TArray<AActor*>&

So for example, my final delegate declaration is this:

 DECLARE_DYNAMIC_MULTICAST_DELEGATE_OneParam(FSelectionChanged, const TArray<UClass*>&, SelectedUnits);

Hope this helps,


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answered Mar 09 '16 at 05:12 PM

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