Re: [RFC] Scalar Type Hinting With Casts (re-opening)

Andrea Faulds wrote (on 15/07/2014):

It’s a shame Nikita’s Exceptions in the Engine RFC failed, as being able to do this would be nice: try {

     $foo = (int!)$foo;

} catch (RecoverableError) {

     $foo = 1;

} Perhaps some sort of similar syntax? (int!)$foo else 0?

I was thinking the same thing myself as I wrote it. My main disagreement with the EngineExceptions as they were proposed was that I think meaningful sub-classes are a must: try {

    $foo = (int!)$foo;

} catch (UnsafeCastException $e) {

    $foo = 1;

} My other thought was to have a syntax for "is this cast safe?", e.g. (int?) but the more I play with it, the more ugly it feels: if ( ! (int?)$foo ) {

      $foo = 1;

} I'd still like to see some readable way of writing that, though. The only built-in function I know of which comes close is filter_var(), which feels like a bit of a sledgehammer: if ( false === filter_var($foo, FILTER_VALIDATE_INT) ) {

     throw new UnsafeCastException;

} Or, to implement a "safe cast", and catch the error case: if ( false === $foo = filter_var($foo, FILTER_VALIDATE_INT) ) {

     $foo = 1;

} Yuck! :P