This solves one of the problems that '!' does, but not the other. If this file is concatenated with one that looks like it would accept a function call, it will be an error, because javascript. e.g.

    (function(){/* stuff */}())
    (function(){/* other stuff */}())

Is interpreted as:

    (function(){/* stuff */)())(function(){/* other stuff */}())

To correct this, you also need a semicolon.

    ;(function() {
        //code here
    })();

Alternatively, if you can stomach it (I can't), you can use the !.