There was some talk about this style a while ago, and I would like to know what you think about this syntax:
$set->union( $set2 ); it would be the same as: $set = $set->union( $set2 ); but if you write it this way: $set3 = $set->union( $set2 ); it doesn't mutate $set. In other words, if a method is called in void context, it mutates the object. If it is called in scalar context, then it is just a function. - Flavio S. Glock
