On Jun 16, 2014, at 3:03 PM, Cameron Zwarich <zwar...@mozilla.com> wrote:
> On Jun 16, 2014, at 2:24 PM, Patrick Walton <pcwal...@mozilla.com> wrote: > >> On 6/16/14 1:04 PM, Sebastian Gesemann wrote: >>> Am 16.06.2014 19:36, schrieb Patrick Walton: >>>> On 6/16/14 7:32 AM, Sebastian Gesemann wrote: >>>>> Assuming this RFC is accepted: How would I have to implement Add for a >>>>> custom type T where moving doesn't make much sense and I'd rather use >>>>> immutable references to bind the operands? >>>> >>>> You don't implement Add for those types. >>> >>> As far as I'm concerned that's anything but a satisfactory answer. I >>> really don't see the point of your RFC. If anything, it seems to make >>> things worse from my perspective. That's why I asked you for some >>> clarifications. Of course, you don't owe me anything. And I hope you >>> don't take this personally. >> >> I don't see much of a use case for `Add` without move semantics. Does anyone >> have any? >> >> Strings and vectors, perhaps, but I would argue that having to call >> `.clone()` on the LHS or RHS (as appropriate) is an improvement, because >> cloning strings and vectors can be very expensive. > > This applies to Mul rather than Add, but if you are multiplying matrices then > you want the destination to not alias either of the sources for vectorization > purposes, so passing by reference is preferred. I stated the right case, but the wrong reason. It’s not for vectorization, it’s because it’s not easy to reuse the storage of a matrix while multiplying into it. Cameron _______________________________________________ Rust-dev mailing list Rust-dev@mozilla.org https://mail.mozilla.org/listinfo/rust-dev
