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Subject: Re: [PHP-DEV] [RFC] Scalar Type Hinting With Casts (re-opening)
From: rowan.collins@gmail.com (Rowan Collins)

Stas Malyshev wrote (on 14/07/2014):
> But I'm not sure why you need this. You accept that if("foo")
> works. Then why "function foo(bool $x) { if($x) { ... " should work
> differently?

The answer - which is definitely a matter of opinion - is that allowing 
any string reduces the usefulness of the type hint.

I realise there is not consensus on whether scalar hints should 
represent validation, cast, or a mixture, but *if* we go down the route 
of validation, then we have to choose which values are valid and which 
are not.

My preference is to keep that strict: the example others have posted of 
some_func($foo & BIT_FLAG) seems no more like a "real" boolean to me 
than some_func(strlen($foo)) or any other expression which yields an 
integer.

In fact, I'd find the behaviour more obvious if it were written 
some_func((bool)$foo & BIT_FLAG) - it makes clear that some_func is not 
itself aware of the flag, that's just the caller's way of making the 
decision. That the type hint encouraged that would therefore seem like a 
Good Thing.

(I'd post that comment on the appropriate sub-thread where that example 
was raised, but don't have time to find it...)

Regards,
-- 
Rowan Collins
[IMSoP]