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Best practice for Python assert
...
To be able to automatically throw an error when x become less than zero throughout the function. You can use class descriptors. Here is an example:
class LessThanZeroException(Exception):
pass
class variable(object):
def __init__(self, va...
What does “hashable” mean in Python?
...y and a set member, because these data structures use the hash value internally.
All of Python’s immutable built-in objects are hashable, while no mutable containers (such as lists or dictionaries) are. Objects which are instances of user-defined classes are hashable by default; they all comp...
How to sort two lists (which reference each other) in the exact same way
...s problem is to use the "decorate, sort, undecorate" idiom, which is especially simple using python's built-in zip function:
>>> list1 = [3,2,4,1, 1]
>>> list2 = ['three', 'two', 'four', 'one', 'one2']
>>> list1, list2 = zip(*sorted(zip(list1, list2)))
>>> list1
...
Why doesn't Python have a sign function?
... it wasn't accepted, because they didn't agree on what it should return in all the edge cases (+/-0, +/-nan, etc)
So they decided to implement only copysign, which (although more verbose) can be used to delegate to the end user the desired behavior for edge cases - which sometimes might require the...
Using variables inside a bash heredoc
... the
lines in the here-document are not expanded. If word is unquoted, all
lines of the here-document are subjected to parameter expansion, command substitution, and arithmetic expansion. [...]
If you change your first example to use <<EOF instead of << "EOF" you'll find that i...
What's “wrong” with C++ wchar_t and wstrings? What are some alternatives to wide characters?
...e wchar_t is a distinct type whose values can represent distinct codes for all members of the largest extended character set specified among the supported locales (22.3.1).
...
UIPanGestureRecognizer - Only vertical or horizontal
I have a view that has a UIPanGestureRecognizer to drag the view vertically. So in the recognizer callback, I only update the y-coordinate to move it. The superview of this view, has a UIPanGestureRecognizer that will drag the view horizontally, just updating the x-coordinate.
...
How to calculate the difference between two dates using PHP?
...ferred way of doing this is like described by jurka below. My code is generally only recommended if you don't have PHP 5.3 or better.
Several people in the comments have pointed out that the code above is only an approximation. I still believe that for most purposes that's fine, since the usage of...
Scala type programming resources
...programming, the computation occurs at compile time. I will try to draw parallels between programming at the value-level and programming at the type-level.
Paradigms
There are two main paradigms in type-level programming: "object-oriented" and "functional". Most examples linked to from here follow...
Calling class staticmethod within the class body?
... def stat_func():
return 42
_ANS = stat_func.__func__() # call the staticmethod
def method(self):
ret = Klass.stat_func()
return ret
As an aside, though I suspected that a staticmethod object had some sort of attribute storing the original function, I had no ...