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Date: Wed, 11 Feb 2015 07:16:26 +0000
Message-ID: <CAL=_i_mDCDOWGyS_AVnPB2paTiVUFoMDqPmbvZ6JBiqqw=vS3Q@mail.gmail.com>
To: Stanislav Malyshev <smalyshev@gmail.com>
Cc: Yasuo Ohgaki <yohgaki@ohgaki.net>, Dmitry Stogov <dmitry@zend.com>, 
	=?UTF-8?Q?Fran=C3=A7ois_Laupretre?= <francois@tekwire.net>, 
	PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=047d7b6da9f01a08a4050ecac870
Subject: Re: [PHP-DEV] Design by Contract
From: pthreads@pthreads.org (Joe Watkins)

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Content-Type: text/plain; charset=UTF-8

> I still don't see what's wrong with just putting the code
at the beginning of the function and whenever you want to check it

That makes inheritance of contracts awkward/impossible/impractical:

class Some {
    public function method() {
        assertOrWhatever($expr);
    }
}

class Other extends Some {
    public function method() {

    }
}

The implementation of Other::method cannot inherit or otherwise make use of
the contracts made by Some.

Putting invariants in the class scope and pre/post conditions in the
function prototype makes inheritance relatively easy.

This seems to answer all your questions.

Cheers
Joe

On Wed, Feb 11, 2015 at 7:11 AM, Joe Watkins <pthreads@pthreads.org> wrote:

> > I think reusing syntax for existing operator in completely unrelated
> context is a big mistake.
>
> I keep hearing that, I agree, but adding keywords presents it's own
> problems.
>
> The keywords can always be changed, maybe they can be a voting option even.
>
> Cheers
> Joe
>
> On Wed, Feb 11, 2015 at 6:56 AM, Stanislav Malyshev <smalyshev@gmail.com>
> wrote:
>
>> Hi!
>>
>> > Please steer clear of using the assert API, and in so doing avoid BC
>> > concerns with the current assert API.
>>
>> The operator can be called something other than "assert", I'm sure the
>> thesaurus has a lot of possibilities.
>>
>> > Please avoid adding a magic method and use the suggested syntax for
>> > invariant.
>> >
>> > class Some {
>> >     require(invariant-expr);
>>
>> I think reusing syntax for existing operator in completely unrelated
>> context is a big mistake. Having code outside of functions is probably
>> not the best idea too.
>>
>> --
>> Stas Malyshev
>> smalyshev@gmail.com
>>
>
>

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