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 <yohg...@ohgaki.net> wrote:
> Hi Joe,
>
> On Tue, Feb 10, 2015 at 4:31 PM, Joe Watkins <pthre...@pthreads.org>
> 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
> yohg...@ohgaki.net
>
