大约有 40,000 项符合查询结果（耗时：0.0338秒） [XML]
django - why is the request.POST object immutable?
...QueryDict class, which implements a full set of mutation methods including __setitem__, __delitem__, pop and clear. It implements immutability by checking a flag when you call one of the mutation methods. And when you call the copy method you get another QueryDict instance with the mutable flag turn...
Is “double hashing” a password less secure than just hashing it once?
...lled "key strengthening" or "key stretching". See en.wikipedia.org/wiki/Key_stretching
– user41871
Dec 7 '08 at 22:40
17
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How do I convert a Ruby class name to a underscore-delimited symbol?
...ow can I programmatically turn a class name, FooBar , into a symbol, :foo_bar ? e.g. something like this, but that handles camel case properly?
...
Difference between numpy.array shape (R, 1) and (R,)
...a view which describes how to interpret the data:
>>> a.flags
C_CONTIGUOUS : True
F_CONTIGUOUS : True
OWNDATA : True
WRITEABLE : True
ALIGNED : True
UPDATEIFCOPY : False
>>> a.dtype
dtype('int64')
>>> a.itemsize
8
>>> a.strides
(8,)
>>> a.sha...
Cast a Double Variable to Decimal
... No because it will throw an OverflowException double vol_y = (double)Decimal.MaxValue + 10E+28D; Console.WriteLine("Convert.ToDecimal(vol_y) = " + Convert.ToDecimal(vol_y));
– ToXinE
Dec 1 '14 at 15:23
...
How can I count the occurrences of a list item?
...by a constant factor of approximately 2.
Here is the script I used:
from __future__ import print_function
import timeit
t1=timeit.Timer('Counter(l)', \
'import random;import string;from collections import Counter;n=1000;l=[random.choice(string.ascii_letters) for x in range(n)]'
...
What is the native keyword in Java for?
...in.c
#include <jni.h>
#include "Main.h"
JNIEXPORT jint JNICALL Java_Main_square(
JNIEnv *env, jobject obj, jint i) {
return i * i;
}
Compile and run:
sudo apt-get install build-essential openjdk-7-jdk
export JAVA_HOME='/usr/lib/jvm/java-7-openjdk-amd64'
javac Main.java
javah -jni Ma...
Parameterize an SQL IN clause
...fun, this time, we'll use $ as the escape character.
select ...
where '|p_%t!r|'
like '%|' + REPLACE(REPLACE(REPLACE( 'p_%t!r' ,'$','$$'),'%','$%'),'_','$_') + '|%' escape '$'
I prefer this approach to escaping because it works in Oracle and MySQL as well as SQL Server. (I usually use the \ b...
What is the volatile keyword useful for?
... volatile:
public class Singleton {
private static volatile Singleton _instance; // volatile variable
public static Singleton getInstance() {
if (_instance == null) {
synchronized (Singleton.class) {
if (_instance == null)
_instance = ...
Package objects
...initions get imported when someone outside of that package imports foo.bar._.
This way you can prevent to require the API client to issue additional imports to use your library effectively - e.g. in scala-swing you need to write
import swing._
import Swing._
to have all the goodness like onEDT a...