add the classname of the messagepart to the mementoname/or replace it with this, with that we can also replace encryption and signature with this function.

no code duplication just run the old method till you delete the old method

I can't do that (yet), it would break code using the BodyPart based memento API, which uses the same key. Killing (or at least massively stripping down) BodyPart is on the TODO list though, which would enable this eventually.

And how would I get to the old code from here? BodyPart is a short-lived object only existing during processing.

ah you mean you can't change it at the moment as long as the implementation is still part of bodyPart. But than the other way round? bodyPart calls the version in MessagePart?

ah sorry - I mixed up with partmetadata. But calling bodyPart -> messagepart would cleanup fix the code duplication.

How would that work? BodyPart is used to construct MessagePart inside process() usually.

Besides the technical difficulty of actually doing this (see above), I don't think this is really a problem here. With the patch series in, we wont be using BodyPart for rendering anymore, making stuff like makeLink() in BodyPart entirely unused and unusable. So we basically have to live with that 8 lines of duplicated code for just a couple of days until I get around to clean up BodyPart.