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nonlocal keyword in Python 2.x
... to implement a closure in Python 2.6 and I need to access a nonlocal variable but it seems like this keyword is not available in python 2.x. How should one access nonlocal variables in closures in these versions of python?
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What is a stack trace, and how can I use it to debug my application errors?
...ead "main" java.lang.NullPointerException
at com.example.myproject.Book.getTitle(Book.java:16)
at com.example.myproject.Author.getBookTitles(Author.java:25)
at com.example.myproject.Bootstrap.main(Bootstrap.java:14)
This is a very simple stack trace. If we start at the begi...
Hidden Features of JavaScript? [closed]
...ters for a function. You can just use the function's arguments array-like object.
function sum() {
var retval = 0;
for (var i = 0, len = arguments.length; i < len; ++i) {
retval += arguments[i];
}
return retval;
}
sum(1, 2, 3) // returns 6
...
How to throw a C++ exception
...
Simple:
#include <stdexcept>
int compare( int a, int b ) {
if ( a < 0 || b < 0 ) {
throw std::invalid_argument( "received negative value" );
}
}
The Standard Library comes with a nice collection of built-in exception objects you can throw. Keep in mind ...
Is there a constraint that restricts my generic method to numeric types?
...
C# does not support this. Hejlsberg has described the reasons for not implementing the feature in an interview with Bruce Eckel:
And it's not clear that the added complexity is worth the small yield that you get. If something you want to do is not dire...
When to use nested classes and classes nested in modules?
I'm pretty familiar with when to use subclasses and modules, but more recently I've been seeing nested classes like this:
5...
How to get the second column from command output?
...
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How to create a windows service from java app
I've just inherited a java application that needs to be installed as a service on XP and vista. It's been about 8 years since I've used windows in any form and I've never had to create a service, let alone from something like a java app (I've got a jar for the app and a single dependency jar - log4j...
Do zombies exist … in .NET?
I was having a discussion with a teammate about locking in .NET. He's a really bright guy with an extensive background in both lower-level and higher-level programming, but his experience with lower level programming far exceeds mine. Anyway, He argued that .NET locking should be avoided on critic...
How to append multiple values to a list in Python
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You can use the sequence method list.extend to extend the list by multiple values from any kind of iterable, being it another list or any other thing that provides a sequence of values.
>>> lst = [1, 2]
>>> lst.append(3)
>>> lst.append(4)
>>> lst
[1, ...