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pythoninheritancepython-2.7introspection

What is the correct way to override the __dir__ method?

This question is meant to be more about __dir__ than about numpy.

I have a subclass of numpy.recarray (in python 2.7, numpy 1.6.2), and I noticed recarray's field names are not listed when diring the object (and therefore ipython's autocomplete doesn't work).

Trying to fix it, I tried overriding __dir__ in my subclass, like this:

def __dir__(self):
    return sorted(set(
               super(MyRecArray, self).__dir__() + \
               self.__dict__.keys() + self.dtype.fields.keys()))

which resulted with: AttributeError: 'super' object has no attribute '__dir__'. (I found here this should actually work in python 3.3...)

As a workaround, I tried:

def __dir__(self):
    return sorted(set(
                dir(type(self)) + \
                self.__dict__.keys() + self.dtype.fields.keys()))

As far as I can tell, this one works, but of course, not as elegantly.

Questions:

  1. Is the latter solution correct in my case, i.e. for a subclass of recarray?
  2. Is there a way to make it work in the general case? It seems to me it wouldn't work with multiple inheritance (breaking the super-call chain), and of course, for objects with no __dict__...
  3. Do you know why recarray does not support listing its field names to begin with? mere oversight?
Solution

  • Have you tried:

    def __dir__(self):
    return sorted(set(
               dir(super(MyRecArray, self)) + \
               self.__dict__.keys() + self.dtype.fields.keys()))