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What are some (concrete) use-cases for metaclasses?
I have a friend who likes to use metaclasses, and regularly offers them as a solution.
19 Answers
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How to override the copy/deepcopy operations for a Python object?
I understand the difference between copy vs. deepcopy in the copy module. I've used copy.copy and copy.deepcopy before successfully, but this is the first time I've actually gone about overloading the __copy__ and __deepcopy__ methods. I've already Googled around and looked through the ...
What is the fastest way to get the value of π?
... fastest π I know of is the one with the digits hard coded. Looking at Pi and Pi[PDF], there are a lot of formulae.
Here is a method that converges quickly — about 14 digits per iteration. PiFast, the current fastest application, uses this formula with the FFT. I'll just write the formula, since...
Build a Basic Python Iterator
...ator protocol, which basically means they provide two methods: __iter__() and __next__().
The __iter__ returns the iterator object and is implicitly called
at the start of loops.
The __next__() method returns the next value and is implicitly called at each loop increment. This method raises a...
Get exception description and stack trace which caused an exception, all as a string
I've seen a lot of posts about stack trace and exceptions in Python. But haven't found what I need.
11 Answers
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How to make an immutable object in Python?
...butes can be accessed via [0] etc., but at least it's considerably shorter and provides the additional advantage of being compatible with pickle and copy.
namedtuple creates a type similar to what I described in this answer, i.e. derived from tuple and using __slots__. It is available in Python 2....
Difference between left join and right join in SQL Server [duplicate]
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Select * from Table1 left join Table2 ...
and
Select * from Table2 right join Table1 ...
are indeed completely interchangeable. Try however Table2 left join Table1 (or its identical pair, Table1 right join Table2) to see a difference. This query should give you mo...
Python dictionary from an object's fields
...class Foo(object):
...
Also, there's a difference between an 'object' and a 'class'. To build a dictionary from an arbitrary object, it's sufficient to use __dict__. Usually, you'll declare your methods at class level and your attributes at instance level, so __dict__ should be fine. For exampl...
How to retrieve a module's path?
...For the file I'm in I had to import another module from the same directory and do as shown here. Does anyone know a more convenient way?
– Ben Bryant
Jan 19 '12 at 18:11
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How do I create a namespace package in Python?
...aries as separate downloads. For example, with the directories Package-1 and Package-2 in PYTHONPATH ,
5 Answers
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