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What is the purpose of the word 'self'?
...way that makes the instance to which the method belongs be passed automatically, but not received automatically: the first parameter of methods is the instance the method is called on. That makes methods entirely the same as functions, and leaves the actual name to use up to you (although self is th...
How to get the request parameters in Symfony 2?
...
The naming is not all that intuitive:
use Symfony\Component\HttpFoundation\Request;
public function updateAction(Request $request)
{
// $_GET parameters
$request->query->get('name');
// $_POST parameters
$request->r...
How to JSON serialize sets?
...s.
As shown in the json module docs, this conversion can be done automatically by a JSONEncoder and JSONDecoder, but then you would be giving up some other structure you might need (if you convert sets to a list, then you lose the ability to recover regular lists; if you convert sets to a dictionar...
How to use a dot “.” to access members of dictionary?
...
Install dotmap via pip
pip install dotmap
It does everything you want it to do and subclasses dict, so it operates like a normal dictionary:
from dotmap import DotMap
m = DotMap()
m.hello = 'world'
m.hello
m.hello += '!'
# m...
Why dict.get(key) instead of dict[key]?
...
It allows you to provide a default value if the key is missing:
dictionary.get("bogus", default_value)
returns default_value (whatever you choose it to be), whereas
dictionary["bogus"]
would raise a KeyError.
If omitted...
decorators in the python standard lib (@deprecated specifically)
...r('always', DeprecationWarning) # turn off filter
warnings.warn("Call to deprecated function {}.".format(func.__name__),
category=DeprecationWarning,
stacklevel=2)
warnings.simplefilter('default', DeprecationWarning) # reset filter
...
What is the copy-and-swap idiom?
...s arguably the most nuanced and difficult. How should it be done? What pitfalls need to be avoided?
The copy-and-swap idiom is the solution, and elegantly assists the assignment operator in achieving two things: avoiding code duplication, and providing a strong exception guarantee.
How does it wor...
Checking images for similarity with OpenCV
...he same image was passed twice, 0% would be returned if the images were totally different.
4 Answers
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When are C++ macros beneficial? [closed]
...nned by the C++ community. In-lined functions, consts and templates are usually a safer and superior alternative to a #define .
...
How do you get the list of targets in a makefile?
...ed rake a bit (a Ruby make program), and it has an option to get a list of all the available targets, eg
20 Answers
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