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Decorators with parameters?
...tion that will take a function and return another function. So it should really return a normal decorator. A bit confusing, right? What I mean is:
def decorator_factory(argument):
def decorator(function):
def wrapper(*args, **kwargs):
funny_stuff()
something_with...
Parse config files, environment, and command-line arguments, to get a single collection of options
...d-line argument parsing ( argparse ). I want to write a program that does all those, and also:
11 Answers
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When is “i += x” different from “i = i + x” in Python?
...
This depends entirely on the object i.
+= calls the __iadd__ method (if it exists -- falling back on __add__ if it doesn't exist) whereas + calls the __add__ method1 or the __radd__ method in a few cases2.
From an API perspective, __iadd__ is supposed to be used fo...
Catch an exception thrown by an async void method
...ET,
is it possible to catch an exception thrown by an async method in the calling method?
6 Answers
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How to retrieve a module's path?
...
import a_module
print(a_module.__file__)
Will actually give you the path to the .pyc file that was loaded, at least on Mac OS X. So I guess you can do:
import os
path = os.path.abspath(a_module.__file__)
You can also try:
path = os.path.dirname(a_module.__file__)
To ge...
Finding the index of an item in a list
... complete. Some caveats about list.index follow. It is probably worth initially taking a look at the documentation for it:
list.index(x[, start[, end]])
Return zero-based index in the list of the first item whose value is equal to x. Raises a ValueError if there is no such item.
The optional argum...
What is the meaning of single and double underscore before an object name?
...at least two leading underscores, at most one trailing underscore) is textually replaced with _classname__spam, where classname is the current class name with leading underscore(s) stripped. This mangling is done without regard to the syntactic position of the identifier, so it can be used to define...
What is the Python equivalent of static variables inside a function?
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there is only one instance of foo - this one function. all invocations access the same variable.
– Claudiu
Nov 10 '08 at 23:49
124
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__getattr__ on a module
...
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__...
Javascript “this” pointer within nested function
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In JavaScript the this object is really based on how you make your function calls.
In general there are three ways to setup the this object:
someThing.someFunction(arg1, arg2, argN)
someFunction.call(someThing, arg1, arg2, argN)
someFunction.apply(someThing...