How to access Interface functions in python

Development Programming & Scripting UI
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1

Hi,

I have a reference to an Actor in python, which implements a custom UInterface.
This interface has some methods I need to call from python, how can I do this?

Here is some example code how I tried it already.
First I get all actors from the scene which implements the interface.
I already checked, but I can’t call the interface function on them directly, so it is necessary to cast the actor, but this doesn’t work, the cast always fails.

actor_array = unreal.GameplayStatics.get_all_actors_with_interface(
            unreal.EditorLevelLibrary.get_editor_world(),
            unreal.MyCustomInterface)
			
for actor in actor_array:
	try:
		interface = unreal.MyCustomInterface.cast(actor)
	except:
		print('cast failed')

Best,
Stephan

2

Using the abc module for abstract base classes seems to do the trick.

from abc import ABCMeta, abstractmethod

class IInterface:
metaclass = ABCMeta

@classmethod
def version(self): return "1.0"
@abstractmethod
def show(self): raise NotImplementedError

class MyServer(IInterface):
def show(self):
print ‘Hello, World 2!’

class MyBadServer(object):
def show(self):
print ‘■■■■ you, world!’

class MyClient(object):

def __init__(self, server):
    if not isinstance(server, IInterface): raise Exception('Bad interface')
    if not IInterface.version() == '1.0': raise Exception('Bad revision')

    self._server = server

def client_show(self):
    self._server.show()

#This call will fail with an exception
try:
x = MyClient(MyBadServer)
except Exception as exc:
print ‘Failed as it should!’

#This will pass with glory
MyClient(MyServer()).client_show()

3

Thanks for your answer, but I think this is not exactly what I’m searching for.

The interface I’m talking about is defined in C++ and inherits form UInterface.
Besides this I have multiple custom C++ classes which are inheriting from AActor and implementing my custom Interface.

4

Here you go:
unreal.Interface.call_method(actor, “YourFunctionNameAsInCpp”, FunctionArgumentsIfAny)