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What are the differences between NP, NP-Complete and NP-Hard?
... the technical definitions require quite some time to understand. First of all, let's remember a preliminary needed concept to understand those definitions.
Decision problem: A problem with a yes or no answer.
Now, let us define those complexity classes.
P
P is a complexity class that repres...
Should I implement __ne__ in terms of __eq__ in Python?
...
this is the right answer (down here, by @aaron-hall). The documentation you quoted does not encourage you to implement __ne__ using __eq__, only that you implement it.
– guyarad
Sep 8 '16 at 13:07
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Understanding the difference between __getattr__ and __getattribute__
...oesn't explicitly manage and do that via __getattr__ method.
Python will call this method whenever you request an attribute that hasn't already been defined, so you can define what to do with it.
A classic use case:
class A(dict):
def __getattr__(self, name):
return self[name]
a = A()...
Is there a replacement for unistd.h for Windows (Visual C)?
...nsole program written for Unix to the Windows platform ( Visual C++ 8.0 ). All the source files include "unistd.h", which doesn't exist. Removing it, I get complaints about misssing prototypes for 'srandom', 'random', and 'getopt'.
I know I can replace the random functions, and I'm pretty sure I ca...
How to import the class within the same directory or sub directory?
I have a directory that stores all the .py files.
13 Answers
13
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Default filter in Django admin
How can I change the default filter choice from 'ALL'? I have a field named as status which has three values: activate , pending and rejected . When I use list_filter in Django admin, the filter is by default set to 'All' but I want to set it to pending by default.
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Usage of __slots__?
What is the purpose of __slots__ in Python — especially with respect to when I would want to use it, and when not?
11 A...
__getattr__ on a module
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A while ago, Guido declared that all special method lookups on
new-style classes bypass __getattr__ and __getattribute__. Dunder methods had previously worked on modules - you could, for example, use a module as a context manager simply by defining __enter__...
Get exception description and stack trace which caused an exception, all as a string
...
See the traceback module, specifically the format_exc() function. Here.
import traceback
try:
raise ValueError
except ValueError:
tb = traceback.format_exc()
else:
tb = "No error"
finally:
print tb
...
List all base classes in a hierarchy of given class?
...ass Foo (whether it is a new-style class or not), how do you generate all the base classes - anywhere in the inheritance hierarchy - it issubclass of?
...