Format
A ||= B
Returns
Value of
(A || B)after it has been assigned to A. This expression can stand by itself; its result does not need to be assigned to anything else.
First A is evaluated. If its value is false, B will be evaluated and assigned to A. If A is true, B will not be evaluated and A will remain unchanged.
Note that this is slightly different from if(!A) A = B if A is a complex expression such as list[index++], because the expression is only evaluated once.
This operator cannot be overloaded.