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Date: Wed, 15 Aug 2012 18:28:55 +0800
Message-ID: <CADajX4AtNgpvNhdy5T9JsCaR_KrZkdUmbpjSL1zKc3FYz2m3aA@mail.gmail.com>
To: Nikita Popov <nikita.ppv@gmail.com>
Cc: Stan Vass <sv_forums@fmethod.com>, Stas Malyshev <smalyshev@sugarcrm.com>, 
	internals@lists.php.net
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Subject: Re: [PHP-DEV] Inline typecasting / typehinting for classes and interfaces
From: aharvey@php.net (Adam Harvey)

On 15 August 2012 18:15, Nikita Popov <nikita.ppv@gmail.com> wrote:
> As already pointed out repeatedly, argument typehints serve the
> purpose of defining an interface. No, they are not required to run the
> code, that's true. But they still serve an important purpose for
> object oriented programming (and, just to make sure that you don't
> miss it again: That purpose is defining the interface). Variable
> typehints do not, as far as I can see.

I was most of the way through writing a much longer e-mail responding
to the original post, but you and Stas have summed it up well, really.
Type hints actually have a use in the object model of PHP in terms of
interface definition. The only uses I can see for these variable hints
are:

1. An informative use for IDEs, as previously noted, which is already
filled adequately by @var documentation.

2. An assertive use in development: effectively, a different way of
writing assert($var instanceof ClassName) to verify your assumptions
on variable types.

Personally, I don't think either of those justify the addition of the featu=
re.

The thing is that even ignoring type hints' interface definition
functionality and treating them as pure syntactic sugar, type hints
have another benefit: if you have several parameters to a function,
type hints allow you to verify their classes in one hit, rather than
having to make several calls to a verification function or implement
something like zpp for objects in userspace. That leads to neater,
shorter code. This feature doesn't have that quality: you can only
hint one variable at a time, so there's not even a significant saving
in time/typing for the developer between (to pick the only version of
the syntax I don't find completely objectionable) "ClassName $var =3D
$object;" and "$var =3D isType($object, 'ClassName');".

In summary, I guess I'm -1 on the feature, and -10=E2=81=B9 on any version =
of
the feature that looks like a typecast. :)

Adam