On 25 Mar 2010, at 21:30, Stefan Marr wrote:
> On 25 Mar 2010, at 16:37, Lukas Kahwe Smith wrote:
>> Hi,
>>
>> this was just brought up on IRC. my understanding is that traits have no
>> concept of properties, but grafts do (all hidden internally). correct?
> Right, the Traits proposal as it is at the moment, avoids the explicit
> discussion of state.
> This is not a restriction per se, but could limit the composability of traits.
>
> To ensure composibility, you would have to resort to abstract methods which
> are implemented by the composing class.
Maybe I should clarify that.
Currently the semantics is implicitly the following:
class Base{
var $a;
}
trait T1 {
var $a;
var $b;
}
trait T2 {
var $a;
var $c;
}
class Composite extends Base {
use T1, T2;
}
and Composite would have the instance variables $a, $b, $c.
The problem would be of course that Base, T1, and T2 could use $a for
completely different things.
Simple, but at the cost of composability/safety.
But for most practical cases that should be 'good enough'. As already
mentioned, if you want stronger guarantees, state accessor methods can be used.
However, I think this implication is not discussed in the RFC, and works just
because PHP can create the fields dynamically. Thus, I used 'var' here in the
example, instead of defining a semantics and handling for public, private,
protected.
Best regards
Stefan
>
> Best regards
> Stefan
>
>
>
> --
> Stefan Marr
> Software Languages Lab
> Vrije Universiteit Brussel
> Pleinlaan 2 / B-1050 Brussels / Belgium
> http://soft.vub.ac.be/~smarr
> Phone: +32 2 629 2974
> Fax: +32 2 629 3525
>
>
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--
Stefan Marr
Software Languages Lab
Vrije Universiteit Brussel
Pleinlaan 2 / B-1050 Brussels / Belgium
http://soft.vub.ac.be/~smarr
Phone: +32 2 629 2974
Fax: +32 2 629 3525
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