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Explaining Python's '__enter__' and '__exit__'
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Using these magic methods (__enter__, __exit__) allows you to implement objects which can be used easily with the with statement.
The idea is that it makes it easy to build code which needs some 'cleandown' code executed (think of it as a try-finally block). Some more ex...
What is the purpose of the single underscore “_” variable in Python?
...cate that part
of a function result is being deliberately ignored (Conceptually, it is being discarded.), as in code like:
label, has_label, _ = text.partition(':').
As part of a function definition (using either def or lambda), where
the signature is fixed (e.g. by a callback or parent class API), ...
Dynamic variable names in Bash
...Fgilrtux] [-p] [name[=value] ...]. You might double-check that you are actually running 4.x and not 3.2.
– chepner
Dec 2 '13 at 16:08
5
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Or versus OrElse
...oth terms. When temp Is DBNull.Value, it can't be compared to zero, so it falls over.
You should use... well, whichever one makes sense.
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Python multiprocessing pool.map for multiple arguments
...rmap method, which accepts a sequence of argument tuples. It then automatically unpacks the arguments from each tuple and passes them to the given function:
import multiprocessing
from itertools import product
def merge_names(a, b):
return '{} & {}'.format(a, b)
if __name__ == '__main__':...
Is there a REAL performance difference between INT and VARCHAR primary keys?
... and a coworker won't budge on the INT AUTO_INCREMENT as a primary key for all tables.
14 Answers
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Changing the default header comment license in Xcode
...sier to just modify the 'organisation name'. It works across the board for all the templates. For anyone who is interested see my answer below.
– Eric Brotto
Feb 19 '11 at 17:48
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How can you programmatically tell an HTML SELECT to drop down (for example, due to mouseover)?
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this is a crying shame - mobile browsers provide an OS specific scrolling list, and I need that to pop up automatically.
– Michael
Sep 25 '17 at 1:22
ad...
What's a good way to extend Error in JavaScript?
...nvironments set the stack property, but fileName and lineNumber are practically useless to be used in inheritance.
So, the minimalistic approach is:
function MyError(message) {
this.name = 'MyError';
this.message = message;
this.stack = (new Error()).stack;
}
MyError.prototype = new Er...
How do you turn off auto-capitalisation in HTML form fields in iOS?
By default, iOS’s keyboard sets the first letter in text form fields (including type=email ) to uppercase. (At least prior to iOS 5.)
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