Componentizing D's garbage collector

[bearophile]

Benjamin Thaut:

> I would prefer a option where the user can specifiy a function 
> to scan classes / structs that contain unions percisely instead 
> of pinning it.
> In generall I would want a option to specify a manual scanning 
> function for any block of GC managed memory, D is a systems 
> programming language after all and specifing a custom scanning 
> functionn can be a lot more effective then assuming the worst 
> possible case for that memory block.

Time ago I suggested an optional standard method for unions of 
structs named as "onGC", that if present is used by the GC at 
run-time to know what to do with the contents of the unions.

Bye,
bearophile