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if A vs if A is not None:
...uivalents 0 or 1. When this method is not defined, __len__() is called, if it is defined, and the object is considered true if its result is nonzero. If a class defines neither __len__() nor __nonzero__(), all its instances are considered true.
On the other hand,
if A is not None:
compares only...
How to generate a random int in C?
...
Note: Don't use rand() for security. If you need a cryptographically secure number, see this answer instead.
#include <time.h>
#include <stdlib.h>
srand(time(NULL)); // Initialization, should only be called once.
int r = rand(); // Ret...
How do I filter ForeignKey choices in a Django ModelForm?
...yset attribute. Depends on how your form is built. If you build an explicit form, you'll have fields named directly.
form.rate.queryset = Rate.objects.filter(company_id=the_company.id)
If you take the default ModelForm object, form.fields["rate"].queryset = ...
This is done explicitly in the ...
open read and close a file in 1 line of code
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You don't really have to close it - Python will do it automatically either during garbage collection or at program exit. But as @delnan noted, it's better practice to explicitly close it for various reasons.
So, what you can do to keep it short, simple an...
event.preventDefault() vs. return false
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return false from within a jQuery event handler is effectively the same as calling both e.preventDefault and e.stopPropagation on the passed jQuery.Event object.
e.preventDefault() will prevent the default event from occuring, e.stopPropagati...
Using Python 3 in virtualenv
Using virtualenv , I run my projects with the default version of Python (2.7). On one project, I need to use Python 3.4.
...
Need to log asp.net webapi 2 request and response body to a database
... {
// log request body
string requestBody = await request.Content.ReadAsStringAsync();
Trace.WriteLine(requestBody);
}
// let other handlers process the request
var result = await base.SendAsync(request, cancellationToken);
if ...
Need to handle uncaught exception and send log file
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Here's the complete solution (almost: I omitted the UI layout and button handling) - derived from a lot of experimentation and various posts from others related to issues that came up along the way.
There are a number of things you need to do:
Handle uncaughtExc...
Concatenating two lists - difference between '+=' and extend()
...on call, which is slightly more expensive in Python than the INPLACE_ADD.
It's really nothing you should be worrying about, unless you're performing this operation billions of times. It is likely, however, that the bottleneck would lie some place else.
...
Android: Rotate image in imageview by an angle
...iew.setImageMatrix(matrix);
This method does not require creating a new bitmap each time.
NOTE: To rotate an ImageView on ontouch at runtime you can
set onTouchListener on ImageView & rotate it by adding last two
lines(i.e. postRotate matrix & set it on imageView) in above code
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