Cpp interface crashes the editor when called.

Development Programming & Scripting C++
1

I’v been using this guid: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums

And when ever I call a function, The editor crashes with this message:
Assertion failed: O->GetClass()->ImplementsInterface(URMInterface::StaticClass())

And pointing on the funciton call line ( Execute_… ).

Code:



auto interface_ = Cast<IRMInterface>(actor_); 
if (interface_)
{
interface_->Execute_StoreLocation(this); //Crashes here
}

Any idea why this is happening?

Also notice the interface is part of a plugin i’m working in and it is in the plugins folder.

2

You should include your interface and class definitions, as the crash error makes it sound like your interface it not setup correctly.

3

You probably wanted to pass actor_ to Execute_StoreLocation instead of this (at least that would make more sense in regards to the cast).
The assertion essentially tells you that the UObject (this) passed to Execute_StoreLocation does NOT implement the interface although it is required to implement it. So in case passing this was intended, make sure that the class implements the IRMInterface.

4

It works now. I had to pass “actor_” instead of “this” into the function. Like this:
interface_->Execute_StoreLocation(actor_);
Thanks for the help guys.

5

Question? Why are you passing the class object too itself?

You are casting actor_ to interface_ then passing actor into the Execute_StoreLocation method of Interface.

6

I should have probably pointed that out too, apologies. The Execute_* functions automatically generated by the UnrealHeaderTool are static and have an UObject* argument. While you don’t have to call them on an instance, it’s perfectly fine to do so although the coding standards you adhere to may discourage that.
Note that it’s still a good idea to cast and check the interface_ first. Otherwise you could easily trigger an assertion (if the UObject* is NULL or the class does not implement the interface).


auto interface_ = Cast<IRMInterface>(actor_); 
if (interface_)
{
	IRMInterface::Execute_StoreLocation(actor_);
}