Tag: Python
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AI seminars — just one of the big changes at LernerPython
July and August are often when people take a break or go on vacation. But for me, this summer has been super busy, full of writing and improving LernerPython based on feedback I’ve gotten from people around the world. And so, I’m here with some big changes I’m making at LernerPython World Headquarters: 1. AI…
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super() without arguments: How Python finds self and the MRO
In Python, invoke super as: Where’s self? Or the MRO? – At compile time, Python adds a __class__ closure cell.– At runtime, super() grabs self from the calling frame — and walks type(self).__mro__ from __class__. No arguments needed (unlike Python 2)!
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Python cooperative inheritance: How super() walks the MRO
Some Python rules for inheritance: – Use super().x() to find the next class with a method “x”– “Next” is defined on the instance, aka type(self).__mro__– Every ancestor class should also use super().x()– This allows multiple parents’ x() methods to run
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Python multiple inheritance: How super() follows the MRO
Python class C inherits from (A, B), and both A.__init__ and B.__init__ invoke super().__init__(). We run C(). It prints “B, A”. How does B.__init__ run? A doesn’t inherit from B. The answer: super() looks at the MRO of C, not A. B isn’t in A.__mro__. But it is in C.__mro__.
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Python multiple inheritance: Why every class needs super()
Multiple inheritance in Python? Make sure all parents run super():
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Python multiple inheritance: Which __init__ actually runs
In a Python child class with two parents, which __init__ runs?
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Python multiple inheritance: Listing parents with __bases__
Does Python allow for multiple inheritance? Yes: And so: C.__bases__ returns: (<class ‘__main__.A’>, <class ‘__main__.B’>)
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Python super() and the MRO: How method lookup climbs the hierarchy
In Python, super() searches the MRO until it finds a match:
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Python inheritance: Skipping super().__init__ loses parent attributes
Didn’t call super() __init__ in your Python class? Attributes normally set on the parent won’t be on the child!
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Python super().__init__: Passing arguments to the parent class
The most common place we use super() in Python? __init__: