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if A vs if A is not None:
...
The statement
if A:
will call A.__nonzero__() (see Special method names documentation) and use the return value of that function. Here's the summary:
object.__nonzero__(self)
Called to implement truth value testing and the built-in operation ...
How do I run all Python unit tests in a directory?
...it test module is of the form test_*.py . I am attempting to make a file called all_test.py that will, you guessed it, run all files in the aforementioned test form and return the result. I have tried two methods so far; both have failed. I will show the two methods, and I hope someone out there ...
How to reliably open a file in the same directory as a Python script
...th(
os.path.join(os.getcwd(), os.path.dirname(__file__)))
The join() call prepends the current working directory, but the documentation says that if some path is absolute, all other paths left of it are dropped. Therefore, getcwd() is dropped when dirname(__file__) returns an absolute path.
Als...
Why are Python's 'private' methods not actually private?
...
The name scrambling is used to ensure that subclasses don't accidentally override the private methods and attributes of their superclasses. It's not designed to prevent deliberate access from outside.
For example:
>>> class Foo(object):
... def __init__(self):
... self....
What is the difference between class and instance attributes?
...just look in each instance's __dict__ and the class's __dict__. It just usually doesn't matter very much whether immutable types are shared or not.
– abarnert
Oct 29 '14 at 22:58
1...
Delete text in between HTML tags in vim?
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And the Surround plugin (vim.org/scripts/script.php?script_id=1697) is awesome when you want to do things like change the surrounding tag (cst) from a <p> to a <div>, for example.
– Kris Jenkins
Nov 21 '10 at 12:45
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Error :Request header field Content-Type is not allowed by Access-Control-Allow-Headers
... extra header. Try prepending the following to your file if you are using PHP:
header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept");
Make sure that you haven't already used header in another file, or you will get a nasty...
How do I profile memory usage in Python?
...
This one has been answered already here: Python memory profiler
Basically you do something like that (cited from Guppy-PE):
>>> from guppy import hpy; h=hpy()
>>> h.heap()
Partition of a set of 48477 objects. Total size = 3265516 bytes.
Index Count % Size % Cumulat...
When is it practical to use Depth-First Search (DFS) vs Breadth-First Search (BFS)? [closed]
...st rules of thumb; you'll probably need to experiment.
Another issue is parallelism: if you want to parallelize BFS you would need a shared datastructure between threads, which is a bad thing. DFS might be easier to distribute even between connected machines if you don't insist on the exact order of...
How to decorate a class?
...2.5, is there a way to create a decorator that decorates a class? Specifically, I want to use a decorator to add a member to a class and change the constructor to take a value for that member.
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