On Wed, 2009-12-02 at 23:03 +0100, Joachim Breitner wrote:
Would it be techically possible and feasible to write instance that do not actually cause a dependency on the package that defines the class resp. the data type? From a distributor point of view, I could live quite well with a setup like this: * When the package providing class Foo is compiled, instances for all interesting data types in the distribution are defined. This means a lot of build-dependencies, but they are not too bad (although annoying). * The generated package does (somehow) not depend on all these data packages. Of course, any part of the code that uses these data types, especially the class instances, are only usable when the corresponding package is also installed. I guess this would need compiler support, to not choke on code that uses unknown data types. * Packages needing an instance Foo Bar would just depend on the packges providing foo and bar, and the instance will be available and functional.
This idea works symmetric: The instances could also be defined in the data type package, with no hard dependency on the package providing the class definition.
Aye, I've thought about a model like this before. I think it's worth considering and working out if it'd be technically feasible. Duncan