Newsgroups: php.internals Path: news.php.net Xref: news.php.net php.internals:82350 Return-Path: Mailing-List: contact internals-help@lists.php.net; run by ezmlm Delivered-To: mailing list internals@lists.php.net Received: (qmail 42630 invoked from network); 10 Feb 2015 08:19:50 -0000 Received: from unknown (HELO lists.php.net) (127.0.0.1) by localhost with SMTP; 10 Feb 2015 08:19:50 -0000 Authentication-Results: pb1.pair.com smtp.mail=dmitry@zend.com; spf=pass; sender-id=pass Authentication-Results: pb1.pair.com header.from=dmitry@zend.com; sender-id=pass Received-SPF: pass (pb1.pair.com: domain zend.com designates 209.85.220.181 as permitted sender) X-PHP-List-Original-Sender: dmitry@zend.com X-Host-Fingerprint: 209.85.220.181 mail-vc0-f181.google.com Received: from [209.85.220.181] ([209.85.220.181:35359] helo=mail-vc0-f181.google.com) by pb1.pair.com (ecelerity 2.1.1.9-wez r(12769M)) with ESMTP id 2D/CC-47508-22FB9D45 for ; Tue, 10 Feb 2015 03:19:50 -0500 Received: by mail-vc0-f181.google.com with SMTP id im6so7080435vcb.12 for ; Tue, 10 Feb 2015 00:19:43 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=2MC+xljw5GV9TjvdsubdISICFGyS7QSZS/a1/vWpQho=; b=RmeRc5EK+Yv2mHUxyfSB2JIBAyXb9fv1ePTAaYidh66aPl/P2xNpWzKjW/ZwImNsli SIR6M9gAl1zV9X+d7JywWj26be18u7yKoagBJmXV7cDD9Ai1QVyNMH/W8Df6J8c0aZUR X8Ynl/7uyJQOL6gWB9T8xEN6VxzjESPArxyQP7vv013bSNgL8lVZdCMhQKuYX/f+kTIO wwdFJvQS58xyPxPhYV9UqMJ0VYwKWiR8fPOW6uQkPV9EcFPZzFEttmntUULg3E4ymCTH t3Zd3Cg4BLUgKVMblQWZUQknFVSmDryk0ItqnlJVqN3bMcPEJAyKxazxLXM+CLcs1JL7 4+CA== X-Gm-Message-State: ALoCoQkIQicJgUFFOCYBVevN9LuKMs8a5O3RWqyKo6Rpde7x6DOlRkoxE5HucZf9PB4w9F0dNmi+R7KEASBVp16fDmfXSKYhjiziO8axNzR1/R7524+AoidmkhsWfwbKVC7gv2JttoUByH46yuy8S7QUmRTLee7Rwg== MIME-Version: 1.0 X-Received: by 10.220.185.193 with SMTP id cp1mr13633518vcb.80.1423556383508; Tue, 10 Feb 2015 00:19:43 -0800 (PST) Received: by 10.52.74.73 with HTTP; Tue, 10 Feb 2015 00:19:43 -0800 (PST) In-Reply-To: References: <54D7ED22.3080001@gmail.com> Date: Tue, 10 Feb 2015 12:19:43 +0400 Message-ID: To: Joe Watkins Cc: Yasuo Ohgaki , Patrick Schaaf , internals Content-Type: multipart/alternative; boundary=089e015386108ea0d6050eb78cce Subject: Re: [PHP-DEV] Design by Contract From: dmitry@zend.com (Dmitry Stogov) --089e015386108ea0d6050eb78cce Content-Type: text/plain; charset=UTF-8 completely agree. contracts must be permanent. Thanks. Dmitry. On Tue, Feb 10, 2015 at 10:40 AM, Joe Watkins wrote: > Example code never works, I can just say that's a bad abstraction, > vertebrate and invertebrate are distinct and abstraction should reflect > that. > > Why should we provide a way to change contracts is the question ? > > It doesn't seem to make sense to do that, a derived class should be able > to define additional contracts, but not change the contracts of it's parent. > > Cheers > Joe > > On Tue, Feb 10, 2015 at 7:36 AM, Yasuo Ohgaki wrote: > >> Hi Joe, >> >> On Tue, Feb 10, 2015 at 4:31 PM, Joe Watkins >> wrote: >> >>> Actually I'm not sure it's at all sane to try to override contracts, I'd >>> actually avoid that completely, so no need to name contracts and no need >>> for magic __invariant. >> >> >> For example, >> >> class Animal { >> protected $legs; >> require($legs >= 0); >> } >> >> class Snake extends Animal { >> // Snake is fine, no leg >> } >> >> class Human extends Animal { >> // 2 legs. $this->leg === 2 >> } >> >> Overriding makes sense for many cases. >> >> Regards, >> >> -- >> Yasuo Ohgaki >> yohgaki@ohgaki.net >> > > --089e015386108ea0d6050eb78cce--