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What does -> mean in Python function definitions?
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And the information is available as a .__annotations__ attribute.
– Martijn Pieters♦
Jan 17 '13 at 13:06
9
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In the shell, what does “ 2>&1 ” mean?
... not redirect stderr to the file, but cmd >> file 2>&1 does. Order matters. In the first case, stderr is redirected to the stdout of the shell (possibly a tty if the command is entered interactively), and then stdout is directed to the file. In the second case, stdout is directed to ...
How to make a cross-module variable?
The __debug__ variable is handy in part because it affects every module. If I want to create another variable that works the same way, how would I do it?
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What exactly does += do in python?
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In Python, += is sugar coating for the __iadd__ special method, or __add__ or __radd__ if __iadd__ isn't present. The __iadd__ method of a class can do anything it wants. The list object implements it and uses it to iterate over an iterable object appending each...
How to override the [] operator in Python?
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You need to use the __getitem__ method.
class MyClass:
def __getitem__(self, key):
return key * 2
myobj = MyClass()
myobj[3] #Output: 6
And if you're going to be setting values you'll need to implement the __setitem__ method too,...
Combining CSS Pseudo-elements, “:after” the “:last-child”
...ks. But, the final content attribute needs to be set to {content:none;} in order to eliminate the final pipe character.
– aridlehoover
Aug 19 '11 at 11:07
2
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How to import a Python class that is in a directory above?
...ithout any necessary relationship to packaging -- then you need to work on __file__ to find out the parent directory (a couple of os.path.dirname calls will do;-), then (if that directory is not already on sys.path) prepend temporarily insert said dir at the very start of sys.path, __import__, remov...
RuntimeError on windows trying python multiprocessing
...l import (i.e. execute) the main module at start. You need to insert an if __name__ == '__main__': guard in the main module to avoid creating subprocesses recursively.
Modified testMain.py:
import parallelTestModule
if __name__ == '__main__':
extractor = parallelTestModule.ParallelExtrac...
How do I get the number of elements in a list?
...objects with a "size" in Python, in particular, have an attribute called ob_size, where the number of elements in the object is cached. So checking the number of objects in a list is very fast.
But if you're checking if list size is zero or not, don't use len - instead, put the list in a boolean co...
How do I determine the size of an object in Python?
...rieve the size and would cause a
TypeError.
getsizeof calls the object’s
__sizeof__ method and adds an additional garbage collector overhead
if the object is managed by the
garbage collector.
See recursive sizeof recipe for an example of using getsizeof() recursively to find the size of containers...