PHP简写语法

Question

I've just came across this on GitHub.

 ($config === NULL) and $config = Kohana::config('email');

Is that the equivalent of

if ($config === NULL) {
    $config = Kohana::config('email');
}

Is this commonplace? Would I expect other developers looking at my code if I used that first way to instantly know what it was doing?

Answer 1

Took me a second to get it, but that should actually work in just about every programming language. Because the "and" or "or" operators are lazily evaluated, if the statement on the left is false, then there's no need to evaluate the rest of the statements because the whole expression will always be false (false and true is false). Likewise, you can do it with "or", but the statement on the left would have to be true, then the one on the right wouldn't be evaluated.

PS: It doesn't really matter in this case that what's on the right isn't really a boolean expression; it'll just take on the truth value of $config