kivy/kivy — pull request #2052 by matham (2014-04-04 16:30:44+00:00)
Title: Warn when factory tries to re-register an existing class with different bases

This fixes #1409

When running the following code a warning should now be issued:

from kivy.app import runTouchApp
from kivy.lang import Builder
from kivy.uix.label import Label

kv = '''
MyClass

'''

class MyClass(Label):
pass

if __name__ == '__main__':
runTouchApp(Builder.load_string(kv))

You'd also get a warning if you first loaded builder before the `MyClass` is decaled in py.