大约有 33,000 项符合查询结果（耗时：0.0347秒） [XML]
Creating a singleton in Python
...Python asking a class what to do by calling __getattr__ when you reference one of it's attributes by doing myclass.attribute.
A metaclass essentially decides what the definition of a class means and how to implement that definition. See for example http://code.activestate.com/recipes/498149/, which ...
Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign
...
This problem is usually caused by one of the following
null values being returned for columns not set to AllowDBNull
duplicate rows being returned with the same primary key.
a mismatch in column definition (e.g. size of char fields) between the database and...
Difference between mkdir() and mkdirs() in java for java.io.File [closed]
Can anyone tell me the difference between these two methods:
3 Answers
3
...
How to condense if/else into one line in Python? [duplicate]
Is there a way to compress an if / else statement to one line in Python?
I oftentimes see all sorts of shortcuts and suspect it can apply here too.
...
Perforce for Git users? [closed]
... new Perforce users coming from Git understand the new world they are in.
One brief detour before we dive in; if you prefer Git you can use Git with Perforce quite well. We provide a tool called Git Fusion that generates Git repositories that are kept in sync with the Perforce server. Git and Perfo...
Why is no one using make for Java?
...and sum up all of the files that are out of date, and then compile them in one go. Make will simply call the java compiler on each individual file. Having make NOT do this requires enough external tooling to really show that Make is not quite up to the task.
That's why alternatives like Ant and Mav...
What is this operator in MySQL?
... Not at all; <=> takes two operands whereas IS (NOT) NULL only takes one; big difference ... it's as useful as = itself in that respect.
– Ja͢ck
Feb 21 '14 at 8:20
...
How is CountDownLatch used in Java Multithreading?
Can someone help me to understand what Java CountDownLatch is and when to use it?
12 Answers
...
Iterate two Lists or Arrays with one ForEach statement in C#
...omething like:
var numbers = new [] { 1, 2, 3, 4 };
var words = new [] { "one", "two", "three", "four" };
var numbersAndWords = numbers.Zip(words, (n, w) => new { Number = n, Word = w });
foreach(var nw in numbersAndWords)
{
Console.WriteLine(nw.Number + nw.Word);
}
As an alternative to...
OnChange event handler for radio button (INPUT type=“radio”) doesn't work as one value
...e variable prev which holds the currently selected radio. A comparison is done within each click handler to decide if the clicked radio is the same as the one stored in prev and if not then the currently clicked radio is stored there. Within the click handler, you have access to the previously selec...