rust-like impl / trait ergonomics?

[alaestor]

I'm not particularly a fan or even a user of Rust, but separating data, interface, and members via impl appears quite pleasing. I'd suspect that similar functionality could be achieved with metaclasses and reflection, but cpp2 also provides an opportunity for exploring this in a more macro-like sense: simply merging the pieces together as needed at transpilation time.

I'm making this discussion less of a suggestion and more just because I'm interested to hear any opinions or prior-art on this.

[MaxSagebaum]

Two points that would worry me from a maintenance/onboarding perspective:

• The struct definition does not let you know that there is an impl block. So you have to be aware that these exist. (There can be multiple ones.) So: How do you know, just a looking at the struct definition, which methods are defined for Rectangle? This would make it quite hard for new people to understand what is possible.
• The same is basically true for traits. You do knot know for which types it is implemented.

It seems like a nice idea. In larger projects the use of this feature has to be probably very restricted in order to make it maintainable.

Just my 2 cents.