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Why is the order in dictionaries and sets arbitrary?
I don't understand how looping over a dictionary or set in python is done by 'arbitrary' order.
6 Answers
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Can someone explain __all__ in Python?
I have been using Python more and more, and I keep seeing the variable __all__ set in different __init__.py files. Can someone explain what this does?
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Elegant ways to support equivalence (“equality”) in Python classes
...om classes it is often important to allow equivalence by means of the == and != operators. In Python, this is made possible by implementing the __eq__ and __ne__ special methods, respectively. The easiest way I've found to do this is the following method:
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Understanding __get__ and __set__ and Python descriptors
I am trying to understand what Python's descriptors are and what they are useful for. I understand how they work, but here are my doubts. Consider the following code:
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How to “perfectly” override a dict?
..._contains__
# free setdefault, __eq__, and so on
import pickle
# works too since we just use a normal dict
assert pickle.loads(pickle.dumps(s)) == s
I wouldn't subclass dict (or other builtins) directly. It often makes no sense, because what you actually want t...
What does if __name__ == “__main__”: do?
... file, it does two things:
it sets a few special variables like __name__, and then
it executes all of the code found in the file.
Let's see how this works and how it relates to your question about the __name__ checks we always see in Python scripts.
Code Sample
Let's use a slightly different cod...
What is the difference between public, protected, package-private and private in Java?
...ess modifiers, namely the default (package private), public , protected and private , while making class and interface and dealing with inheritance?
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Calling parent class __init__ with multiple inheritance, what's the right way?
...asses.
In the direct call approach, C.__init__ can call both A.__init__ and B.__init__.
When using super(), the classes need to be designed for cooperative multiple inheritance where C calls super, which invokes A's code which will also call super which invokes B's code. See http://rhettinger.w...
Difference between __getattr__ vs __getattribute__
I am trying to understand when to use __getattr__ or __getattribute__ . The documentation mentions __getattribute__ applies to new-style classes. What are new-style classes?
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Why does the C preprocessor interpret the word “linux” as the constant “1”?
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In the Old Days (pre-ANSI), predefining symbols such as unix and vax was a way to allow code to detect at compile time what system it was being compiled for. There was no official language standard back then (beyond the reference material at the back of the first edition of K&R), a...