On Mon, Jan 27, 2014 at 08:33:57PM +0100, Gábor Lehel wrote: > I think this question has a more general form, namely: when should I pass > by value and when using &move/&my? I expect this will come up quite a bit > if we add the latter.
Yes, I agree. The main reason to use `&move/&my` is to permit moves of dynamically sized types. In the case of once closures, that is a trait type. Given that, I have wondered if we can do without it, and instead say that (e.g.) passing a DST as a by value argument is legal. Without a region, though, we'd need some other rules to prevent that DST from leaking. For example, you can pass a DST as an input parameter, but you cannot have a local variable, field, or return type of DST type. The last time I thought this through, those rules (or something like them) seemed onerous, but now they seem quite reasonable to me. (More or less the same as our old reference mode parameters.) They support the important use case of passing in a (unboxed) `OnceFn` object and permitting it to be called. Niko _______________________________________________ Rust-dev mailing list Rust-dev@mozilla.org https://mail.mozilla.org/listinfo/rust-dev
