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Date: Wed, 11 Aug 2010 21:29:46 +0200
Message-ID: <AANLkTimiKbBOi3ehj_ZujTjt12us-+FsacMvNqeOUCd0@mail.gmail.com>
To: Alexey Zakhlestin <indeyets@gmail.com>
Cc: Stas Malyshev <smalyshev@sugarcrm.com>, Internals <internals@lists.php.net>
Content-Type: text/plain; charset=ISO-8859-1
Subject: Re: [PHP-DEV] Strict typing
From: phpwnd@gmail.com (Josh Davis)

On 11 August 2010 19:11, Alexey Zakhlestin <indeyets@gmail.com> wrote:
> Did you read second RFC? The one which is about "so called" weak typehinting.
> Stas (and a lot of people on this list) prefer it.
> http://wiki.php.net/rfc/typecheckingstrictandweak

Yes of course, but reposting that link is a good idea. :)

> If you did, can you tell if there is some case, when it doesn't work for you?

If I'm using type checking as a sanity check then it doesn't work as
soon as it accepts "1" for an int. The described "weak typehinting" is
good if you're looking for a way to validate input. However, it does
not work if you're trying to make sure that Stuff Is Going As
Planned(tm). For example, consider a protected method
getTheNextNTokens(int $n) which is part of some tokenizer or
something. It is a protected method and you never write
getTheNextNTokens("2") so if it ever receives something that is not an
integer, it means that there's a subtle bug somewhere. In that case,
"strict typehinting" buys you peace of mind.

If your function lives in a controlled environment (e.g. private
methods, or because your specifications require to use the filter
extension to validate input) then checking for the type of a variable
offers more protection against the unexpected than checking for its
contents. Of course, it's not an absolute protection, just like making
a method private does not guarantee that a user [of your code] won't
extend it to make it public or use ReflectionMethod to make it
accessible. It's just another way to defend against the unexpected.

I hope it answers your question :)