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Is there a Python caching library?
...
From Python 3.2 you can use the decorator @lru_cache from the functools library.
It's a Last Recently Used cache, so there is no expiration time for the items in it, but as a fast hack it's very useful.
from functools import lru_cache
@lru_cache(maxsize=256)
def f(x):
...
Inverse dictionary lookup in Python
...s slow as yours, because it creates a list from the dict twice.
key = dict_obj.keys()[dict_obj.values().index(value)]
Or if you prefer brevity over readability you can save one more character with
key = list(dict_obj)[dict_obj.values().index(value)]
And if you prefer efficiency, @PaulMcGuire's...
How does Python's super() work with multiple inheritance?
...including two earlier attempts).
In your example, Third() will call First.__init__. Python looks for each attribute in the class's parents as they are listed left to right. In this case, we are looking for __init__. So, if you define
class Third(First, Second):
...
Python will start by looki...
How to retrieve a module's path?
...
import a_module
print(a_module.__file__)
Will actually give you the path to the .pyc file that was loaded, at least on Mac OS X. So I guess you can do:
import os
path = os.path.abspath(a_module.__file__)
You can also try:
path ...
Purpose of Python's __repr__
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__repr__ should return a printable representation of the object, most likely one of the ways possible to create this object. See official documentation here. __repr__ is more for developers while __str__ is for end users.
A ...
How to invoke the super constructor in Python?
...on-3.x the process has been simplified:
Python-2.x
class A(object):
def __init__(self):
print "world"
class B(A):
def __init__(self):
print "hello"
super(B, self).__init__()
Python-3.x
class A(object):
def __init__(self):
print("world")
class B(A):
def __init__(self):
print...
C/C++ line number
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You should use the preprocessor macro __LINE__ and __FILE__. They are predefined macros and part of the C/C++ standard. During preprocessing, they are replaced respectively by a constant string holding an integer representing the current line number and by the cu...
How does __proto__ differ from constructor.prototype?
...bject layout
The most surprising thing for me was discovering that Object.__proto__ points to Function.prototype, instead of Object.prototype, but I'm sure there's a good reason for that :-)
I paste the code mentioned in the image here as well for if anyone wants to test it. Note that some propert...
计算统计特征（正态分布）函数及实例 - C/C++ - 清泛网 - 专注C/C++及内核技术
...实例main函数：#include "stdafx.h"#include "stdev.h"#include <map>int _tmain(int argc, _TCHAR* argv[]){std::map<int, int> map_...main函数：
#include "stdafx.h"
#include "stdev.h"
#include <map>
int _tmain(int argc, _TCHAR* argv[])
{
std::map<int, int> map_test;
map_test[0] = 100;...
__lt__ instead of __cmp__
Python 2.x has two ways to overload comparison operators, __cmp__ or the "rich comparison operators" such as __lt__ . The rich comparison overloads are said to be preferred, but why is this so?
...