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Python read-only property
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Generally, Python programs should be written with the assumption that all users are consenting adults, and thus are responsible for using things correctly themselves. However, in the rare instance where it just does not make sense for an attribute to be settable ...
How to make an immutable object in Python?
Although I have never needed this, it just struck me that making an immutable object in Python could be slightly tricky. You can't just override __setattr__ , because then you can't even set attributes in the __init__ . Subclassing a tuple is a trick that works:
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Why is __init__() always called after __new__()?
... trying to streamline one of my classes and have introduced some functionality in the same style as the flyweight design pattern .
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Getting attributes of a class
...the inspect module. getmembers and the various tests should be helpful.
EDIT:
For example,
class MyClass(object):
a = '12'
b = '34'
def myfunc(self):
return self.a
>>> import inspect
>>> inspect.getmembers(MyClass, lambda a:not(inspect.isroutine(a)))
[('__cl...
How to override the copy/deepcopy operations for a Python object?
... , decimal.py , and fractions.py ), but I'm still not 100% sure I've got it right.
7 Answers
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How do I implement __getattribute__ without an infinite recursion error?
...ble in a class, but return all others normally. How do I accomplish this with __getattribute__ ?
6 Answers
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Difference between __str__ and __repr__?
...Alex summarized well but, surprisingly, was too succinct.
First, let me reiterate the main points in Alex’s post:
The default implementation is useless (it’s hard to think of one which wouldn’t be, but yeah)
__repr__ goal is to be unambiguous
__str__ goal is to be readable
Container’s __s...
What's the difference between __PRETTY_FUNCTION__, __FUNCTION__, __func__?
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__func__ is an implicitly declared identifier that expands to a character array variable containing the function name when it is used inside of a function. It was added to C in C99. From C99 §6.4.2.2/1:
The identifier __func__ is implicitly d...
Elegant ways to support equivalence (“equality”) in Python classes
When writing custom 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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Python (and Python C API): __new__ versus __init__
...m about to ask seems to be a duplicate of Python's use of __new__ and __init__? , but regardless, it's still unclear to me exactly what the practical difference between __new__ and __init__ is.
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