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How to check for an undefined or null variable in JavaScript?
...xistingObj.someUndefProperty. An undefined property doesn't yield an error and simply returns undefined, which, when converted to a boolean, evaluates to false. So, if you don't care about
0 and false, using if(obj.undefProp) is ok. There's a common idiom based on this fact:
value = obj.prop || de...
Constructors vs Factory Methods [closed]
...ns: Elements of Reusable Object-Oriented Software by Gamma, Helm, Johnson, and Vlissides.
Use the Factory Method pattern when
a class can't anticipate the class of objects it must create
a class wants its subclasses to specify the objects it creates
classes delegate responsibility to one of sever...
Python circular importing?
... specific to your case: Try changing entities/post.py to do import physics and then refer to physics.PostBody rather than just PostBody directly. Similarly, change physics.py to do import entities.post and then use entities.post.Post rather than just Post.
...
NUnit vs. Visual Studio 2008's test projects for unit testing [closed]
I am going to be starting up a new project at work and want to get into unit testing. We will be using Visual Studio 2008, C#, and the ASP.NET MVC stuff. I am looking at using either NUnit or the built-in test projects that Visual Studio 2008 has, but I am open to researching other suggestions. ...
How do you performance test JavaScript code?
...e user/client. For example, we had a project with an Ext accordion that expanded to show some data and then a few nested Ext grids. Everything was actually rendering pretty fast, no single operation took a long time, there was just a lot of information being rendered all at once, so it felt slow to...
What does the “at” (@) symbol do in Python?
...
An @ symbol at the beginning of a line is used for class, function and method decorators.
Read more here:
PEP 318: Decorators
Python Decorators
The most common Python decorators you'll run into are:
@property
@classmethod
@staticmethod
If you see an @ in the middle of a line, that's ...
ARC and bridged cast
...ained <CFType>) op or alternatively CFBridgingRetain(op) is used to hand an NSObject over to CF-land while giving it a +1 retain count. You should handle a CFTypeRef you create this way the same as you would handle a result of CFStringCreateCopy(). This could also be represented by CFRetain((_...
How do you cast a List of supertypes to a List of subtypes?
...er to another. However, you can cast through an intermediate wildcard type and it will be allowed (since you can cast to and from wildcard types, just with an unchecked warning):
List<TestB> variable = (List<TestB>)(List<?>) collectionOfListA;
...
Is there an alternative to bastard injection? (AKA poor man's injection via default constructor)
...
As far as I understand, this question relates to how to expose a loosely coupled API with some appropriate defaults. In this case, you may have a good Local Default, in which case the dependency can be regarded as optional. One way to deal with...
What's the difference between “Normal Reload”, “Hard Reload”, and ...
... do re-download every JavaScript file, image, text file, etc.
Empty Cache and Hard Reload
Obviously, if the cache is empty then it will have to do a hard reload. This will again force the browser to re-download everything. However, if the page makes any after-the-fact downloads via JavaScript that ...