thanks this is cool :) Ideally I would like to have a deep look at the trait implementation and understand also how we can make it more pluggable but I do not have the time for that. Stef On Aug 29, 2010, at 7:21 AM, jaayer wrote:
I recently ran into a situation where I needed a class to behave like a subclass of Magnitude, understanding <, <= and company, that could not be a subclass of Magnitude because it already had a custom superclass. I had two options: use composition to create a Magnitude subclass that implements Magnitude's abstract methods by forwarding to an instance of the class in question, or implement all of Magnitude's message in the class. While the first choice was clearly preferable to the second, I would have liked to have had a third: use a Trait to graft comparability on to the class. While I know some people here dislike Traits, I don't think a class should have to inherit from Magnitude just so its instances can be easily compared with one another.
Enclosed is a fileout of a Trait named TComparable. It contains Magnitude's "comparing" and "testing" messages with the argument names and method comments changed where needed. If Magnitude is to be reimplemented using it, then Magnitude's class template must be changed accordingly, and perhaps its old implementations of the "comparing" and "testing" messages should be removed as well.
Additionally, I discovered that this message: isMetacelloConfig ^ false
needs to be added to Trait, if it hasn't been already, otherwise you get an error when right-clicking on one (at least in 1.1).<TComparable.st>_______________________________________________ Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project