Serialization for D. Comments, please!

[grauzone]

> I'm looking at what it would take to get by without a mixin in the types 
> (someone objected to that) without loosing anything I want. with a mixin 
> in the class, I've already got a solution.

Though I never questioned that you do need compile time access to the 
serialized code, and that (at least if you don't want to force the user 
to implement interfaces) some code knowing the static type must be run 
at initialization.