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How can I add new keys to a dictionary?
...ted to strings). dict.update can also take another dictionary, but I personally prefer not to explicitly create a new dictionary in order to update another one.
– bgusach
Feb 13 '19 at 8:38
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Checking for empty queryset in Django
...if not my_objects: to demonstrate that this is how they do it in the docs. All else is utterly irrelevant so I do not get your point. They could as well make a thousand queries and it would still be totally irrelevant as this is not the point of this answer, with which I make clear that I agree.
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Keyboard Interrupts with python's multiprocessing Pool
...s to set up the worker processes to ignore SIGINT altogether, and confine all the cleanup code to the parent process. This fixes the problem for both idle and busy worker processes, and requires no error handling code in your child processes.
import signal
...
def init_worker():
signal.sign...
Is there a short contains function for lists?
...her have said, you may also be interested to know that what in does is to call the list.__contains__ method, that you can define on any class you write and can get extremely handy to use python at his full extent.
A dumb use may be:
>>> class ContainsEverything:
def __init__(self):...
Counting array elements in Python [duplicate]
... in an array, because contrary to logic array.count(string) does not count all the elements in the array, it just searches for the number of occurrences of string.
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TypeError: 'NoneType' object is not iterable in Python
... Correct, But the common scenario author intended here is totally to skip the for loop instead of raising an exception. Python's design is flawed here. When None is treated as an iterable it must return empty list at least. This exception never helped anyone in real life other than m...
Check if event exists on element [duplicate]
...econd argument feed 'events' and that will return an object populated with all the events such as 'click'. You can loop through that object and see what the event handler does.
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How does RegexOptions.Compiled work?
...methods on the Regex class.
For example: Regex.Replace, Regex.Match etc.. all use the Regex cache.
The size of the cache can be increased by setting Regex.CacheSize. It accepts changes in size any time during your application's life cycle.
New regular expressions are only cached by the static hel...
When do I use a dot, arrow, or double colon to refer to members of a class in C++?
...d for three different scenarios that are always well-defined. Knowing this allows you to immediately know quite a lot about a and b just by looking at a::b, a.b, or a->b, respectively, in any code you look at.
a::b is only used if b is a member of the class (or namespace) a. That is, in this c...
Delete files older than 15 days using PowerShell
...is in the title of this post), but here's some code that will first delete all of the files older than 15 days, and then recursively delete any empty directories that may have been left behind. My code also uses the -Force option to delete hidden and read-only files as well. Also, I chose to not use...