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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...
Python read-only property
...he new-style classes.
Example:
>>> class A(object):
... def __init__(self, a):
... self._a = a
...
... @property
... def a(self):
... return self._a
...
>>> a = A('test')
>>> a.a
'test'
>>> a.a = 'pleh'
Traceback (most recent call la...
What's the (hidden) cost of Scala's lazy val?
...nswered Jun 15 '10 at 7:51
oxbow_lakesoxbow_lakes
127k5252 gold badges305305 silver badges442442 bronze badges
...
How to find the size of localStorage
...
Execute this snippet in JavaScript console (one line version):
var _lsTotal=0,_xLen,_x;for(_x in localStorage){ if(!localStorage.hasOwnProperty(_x)){continue;} _xLen= ((localStorage[_x].length + _x.length)* 2);_lsTotal+=_xLen; console.log(_x.substr(0,50)+" = "+ (_xLen/1024).toFixed(2)+" KB")...
What's the UIScrollView contentInset property for?
... an informative screenshot (fig 1-3) - I'll replicate it via text here:
_|←_cW_→_|_↓_
| |
---------------
|content| ↑
↑ |content| contentInset.top
cH |content|
↓ |content| contentInset.bottom
|content| ↓
---------------
_|_______|___
↑
(cH = ...
Is there a replacement for unistd.h for Windows (Visual C)?
... file.
Here's a starting point. Please add definitions as needed.
#ifndef _UNISTD_H
#define _UNISTD_H 1
/* This is intended as a drop-in replacement for unistd.h on Windows.
* Please add functionality as neeeded.
* https://stackoverflow.com/a/826027/1202830
*/
#include <stdlib.h>
#inc...
std::function and std::bind: what are they, and when should they be used?
...ere are two left to go.
You can use std::bind to get g:
auto g = bind(f, _1, 4, _2);
This is more concise than actually writing a functor class to do it.
There are further examples in the article you link to. You generally use it when you need to pass a functor to some algorithm. You have a fun...
Does Flask support regular expressions in its URL routing?
...flask import Flask
from werkzeug.routing import BaseConverter
app = Flask(__name__)
class RegexConverter(BaseConverter):
def __init__(self, url_map, *items):
super(RegexConverter, self).__init__(url_map)
self.regex = items[0]
app.url_map.converters['regex'] = RegexConverter
...
KIO4_Gradient 拓展：布局中的颜色渐变 - App Inventor 2 中文网 - 清泛IT...
http://kio4.com/appinventor/287_extension_gradiente_color.htm
- 让我们看一下在布局中制作颜色渐变的扩展。- 我们放置一个布局，然后在该扩展的块中插入该布局的名称，放置一个包含所需颜色的列表，以及一个从 1 到 8 的数字，用于表示...
Python, creating objects
... ""
# The class "constructor" - It's actually an initializer
def __init__(self, name, age, major):
self.name = name
self.age = age
self.major = major
def make_student(name, age, major):
student = Student(name, age, major)
return student
Note that even tho...