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inheritancepsychopy

metaclass error when inheriting from psychopy.visual.DotStim

I'm trying to inherit a class from visual.DotStim like this 

class JitterDots(visual.DotStim):
...

I always get the infamous metaclass error:

TypeError: Error when calling the metaclass bases metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases

I understand you can fix this by merging all base classes' metaclasses, but I can't see where DotStim or its bases use any metaclasses, so I'm really confused by this.

Any suggestions?

Solution

  • This seems to be working for me:

    from psychopy.visual import dot

class JitterDots(dot.DotStim):
    pass

    Unrelated to your immediate question, but still a possible pitfall: I also noticed that some of the bases/parents of DotStim inherit directly from object, but never initialize their parent via super() -- although super() is called in DotStim.__init__(). However, "doing so will cause other classes' __init__ methods to not be called", according to https://fuhm.net/super-harmful/