Re: RFC: Traits for PHP - Stateful Traits

Hi, Andi Gutmans schrieb:

a) I think Traits should be able to act as a self-contained behavior which can always be expected to work. For example if I want a Counter behavior I would like

that not to depend on the properties in the containing class. While I don't

think we should enable public nor protected properties in Traits I think allowing for private properties in Traits would come in very handy. It also

is no problem when it comes to mangling as we can use the Trait name. class Trait { private $counter = 0; function getNextSerialNumber() { return $this->counter++; } } I strongly recommend not to support protected/public and not to even get into the discussion of dealing with conflicts of such properties. But I think private is very useful. Hope I got it right, since your example is a class?

Ok, stateful traits are useful in the sense of having self-contained units of reuse. Personally, I prefer them over stateless traits. But, here we will get additional confusion. You don't like to handle with visibilities of properties? Fine :) One way to do stateful traits is described in http://www.iam.unibe.ch/~scg/Archive/Papers/Berg07eStatefulTraits.pdf But the way you have proposed is stricter and may be sufficient. To avoid confusion and misconception I would like to change your proposal a bit. Private does suggest a semantics like methods, and would require to apply the flattening on properties like on methods. Since we do not like to handle conflicts, this would have to be done a bit different, in my opinion. Let's change `private to local`: trait TCounter { local $counter = 0;

    function getNextSerialNumber() {
    return $this->counter++;

} } class Website { use TCounter; } The resulting composition would have a property resulting from the TCounter property, but is only accessible from a method of the specific trait, i.e., it is composition local. Just an additional though :) Kind Regards Stefan