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Date: Wed, 13 May 2015 23:37:18 +0200
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Subject: RE: [PHP-DEV] Proposal: interfaces for object to scalar type casting
From: francois@php.net (=?utf-8?Q?Fran=C3=A7ois_Laupretre?=)

Hi,

> De : Guido Contreras Woda [mailto:guiwoda@gmail.com]
>=20
> Multiple frameworks and libraries define interfaces or objects that =
wrap
> around some scalar value and add behavior, the most common case being
> arrays and Collection / Hash[Set|List] objects. Although this objects
> benefit from the possibility of having behavior themselves, sometimes =
the
> implementation is outside our project scope (an external dependency) =
and
> interaction between this object and other blocks of code that expect =
scalar
> types usually needs to be controlled by the user, which adds the =
necessity
> for adapters or some sort of mediator.
>=20
> Now that we have the ability to hint return types, a common interface =
could
> be built that, given an object that implements it, lets userland code =
use
> this object as if it were the scalar type it is wrapping. Unboxing the
> object is pretty easy, and I wouldn't go as far as proposing =
interfaces for
> rebuilding the object itself (not now, at least).
>=20
> So, what do you think of a set of interfaces that allow userland =
objects to
> be used as scalar types?

First, we probably don't need anything for arrays. The Iterator =
interface family already provides everything we need to consider an =
object as an array.

For other scalar types, while I agree casting should be supported, I =
don't like the solution of creating new methods. I would prefer always =
calling __toString() and then, convert the string to the desired type. =
So, (int)$object would just be a shortcut for (int)(string)$object. =
Quite easy to implement, no new method, just need to enrich the =
convert_to_xxx() functions to go through convert_to_string first. I =
already had this idea for 7.0 but missed time. Maybe for 7.1.

I also think it's more consistent as an object could not be transformed =
to different unrelated values when cast to different scalar types. If =
$object, when cast to int, becomes 10 and, when cast to string, becomes =
'foo', is it consistent in such a loose typing system ? So, I prefer =
that, by construction, (int)$obj always gives the same value as =
(int)(string)$obj.

Regards

Fran=C3=A7ois