simplegeneric => singledispatch: backward compatibility

[franzlst]

With the change from simplegeneric to singledispatch, gaphas is no longer backward compatible with code that registers custom types, as you now need to call register instead of when_type.

This is fine, as you increase the minor version.

I was just wondering, whether you think there is an easy way for other software not requiring any code changes. Maybe somehow monkeypatching singledispatch? Doesn't sound like the best solution :-D

[amolenaar]

I ran into the same issue when I tried running Gaphor with the Gaphas-master. I haven't sorted out a nice way to do it.

I agree that monkey-patching should not be the way to go, but in order to not break the interface, when_type() should be present somehow. If when_type would be available, it should go with a big deprecation warning, as I like to get rid of it ASAP.

[amolenaar]

I added a small compatibility layer in adf3bdc.

[franzlst]

Cool! And a clean solution 👍

[franzlst]

when_type was accepting multiple types/classes, your wrapper only accepts one. Maybe you could change this...? 😳 😶

[amolenaar]

I think that's easy to update. I did not dig that deep into the when_type api :).

BTW. The GenericType.default property is no longer there, so that would require a change. I'm not sure if we should add that back as well (preferably not).

[franzlst]

Thank you!