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Date: Sun, 13 Jul 2014 16:10:33 +0100
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Subject: Re: [PHP-DEV] [RFC] Scalar Type Hinting With Casts (re-opening)
From: rowan.collins@gmail.com (Rowan Collins)

On 13/07/2014 15:41, Zeev Suraski wrote:
> In other words, if someone types in '12a'
> (by mistake or intentionally), I think it's a very sane behavior to just
> treat it as 12, as opposed to forcing me (the developer) to write error
> handling code with a try/catch block, and a fairly hairy try/catch block
> too.

Sure, but what if they type 'abc'? You *might* want that to be cast as 0 
(not for an age input, obviously, but perhaps a "minimum price" field), 
so you could argue for *always* casting, rather than erroring. On the 
other hand, you might well want to default to some other value, which 
would require custom handling somewhere.

If you want to allow for people *accidentally* adding letters, why 
accept '12a' but not 'a12'? If you want a "best guess", surely both 
should come out as 12 (whereas an integer cast would give you 0 for the 
latter). If you want validation, both are equally invalid.

To my mind, the more values are let through with a bit of hand-waving, 
the less useful the check is. The worst culprit for this is 
is_numeric(), which sounds like a useful general-purpose function, but 
will happily accept exotic numbers like '-1e-10', and thus is almost 
never what you want.

> Your example of "12 " (that I didn't even think about before) is an
> even a more likely scenario, but I think there's no strong reason not to
> allow both.

I disagree, and think there's a stronger argument to be made for 
handling whitespace as a special case. Notably, int casts already do so 
- (int)' 12' (leading space) is 12, but (int)'a12' (leading non-digit) 
is 0 (no such special case is needed for trailing whitespace, because 
any trailing characters are ignored.)

Regards,

-- 
Rowan Collins
[IMSoP]