What does ||= mean? [duplicate]

Question

Possible Duplicate:
What does ||= (or equals) mean in Ruby?
What does ||= mean?

I have just started learning RubyMotion and in a lot of examples I see the ||= syntax. What does this mean?

Here is an example:

def window
  @window ||= begin
    w = UIWindow.alloc.initWithFrame UIScreen.mainScreen.bounds
    w.rootViewController = @navigationController
    w
end

It is difficult to search symbols, google ignored the symbols in my query.

Answer 1

It is an assignment operator which means: or assign this value to a variable.

So if you did something like x ||= ythis meansx || x = y so if x is nil or false set x to be the value of y.