Sometimes you see something like this in Ruby source code:
var1 ||= 123
Which is a pretty awesome way to express this:
var1 = var1 || 123
What in turn means:
var1 = 123 if !var1
Or the long version:
if !var1
var1 = 123
end
And in the case you only speak PHP:
<?php
if(!$var1){
$var1 = 123;
}