On 29/09/20 19:55, Marc-André Lureau wrote: > My understanding of what you propose is: > - ForeignConvert::with_foreign > - FromForeign::from_foreign (with implied into_native) > And: > - ForeignConvert::as_foreign (with the BorrowedPointer/stash-like) > - ToForeign::to_foreign + ForeignConvert::as_foreign_mut (which seems > wrongly designed in your proposal and unnecessary for now)
Might well be, but how is it wrong? (I'd like to improve). > I don't have your head, so I find it hard to remember & work with. It> uses > all possible prefixes: with_, from_, as_, as_mut, to_, and into_. > That just blows my mind, sorry :) Ahah I don't have your head either! The idea anyway is to reuse prefixes that are common in Rust code: * with_: a constructor that uses something to build a type (think Vec::with_capacity) and therefore takes ownership * as_: a cheap conversion to something, it's cheap because it reuses the lifetime (and therefore takes no ownership). Think Option::as_ref. * from_/to_: a copying and possibly expensive conversion (that you have to write the code for). Because it's copying, it doesn't consume the argument (for from_) or self (for to_). * into_: a conversion that consumes the receiver It may well be over the top. > Then, I don't understand why ForeignConvert should hold both the "const > *P -> T" and "&T -> const *P" conversions. Except the common types, > what's the relation between the two? Maybe I'm wrong, but why would you need just one? > Finally, I thought you introduced some differences with the stash > design, but in fact I can see that ForeignConvert::Storage works just > the way as ToPtr::Storage. So composition should be similar. Only your > example code is more repetitive as it doesn't indirectly refer to the > trait Storage the same way as glib-rs does (via <T as ToPtr>::Storage). Yes, that's the main difference. I removed Storage because I didn't want to force any trait on BorrowedPointer's second type argument. It seemed like a generic concept to me. The other difference is that Stash is a tuple while BorrowedPointer is a struct and has methods to access it. Stash seems very ugly to use. > I am not making any conclusions yet, but I am not exactly happily going > to switch to your proposal yet :) Sure, no problem. Paolo
