std: Stabilize IteratorExt::cloned
#23462
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r? @aturon (rust_highfive has picked a reviewer for you, use r? to override) |
This commit stabilizes the `cloned` iterator after tweaking the signature to require that the iterator is over `&T` instead of `U: Deref<T>`. This method has had time to bake for awhile now and it's not clear whether the `Deref` bound is worth it. Additionally, there aren't clear conventions on when to bound and/or implement the `Deref` trait, so for now the conservative route is to require references instead of `U: Deref<T>`. To change this signature to using `Deref` would technically be a backwards-incompatible change, but it is doubtful that any code will actually break in practice.
alexcrichton
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I assume Option::cloned will go the same way, since it is very much the same. |
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@alexcrichton I have mixed feelings about this signature change -- it's both less flexible, and possibly less clear. Can you expand a bit on the motivation for the change? (I do agree that we don't have a convention yet, but conventions often arise from examples like this.) That said, I don't care too much either way. cc @gankro |
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The primary motivation of Deref was to unify & and &mut. Granted: I can't think of any place where you'd only have an &mut but couldn't do & (maybe a generic context...?). Being able to rip through Box's/Rc's/Whatever is just gravy that I wasn't super concerned with. |
I do agree that the signature went a bit south, I was not super happy that type/lifetime parameters needed to be added.
My main motivation was that we have very few functions which are abstract over
If we stabilize |
…uron This commit stabilizes the `cloned` iterator after tweaking the signature to require that the iterator is over `&T` instead of `U: Deref<T>`. This method has had time to bake for awhile now and it's not clear whether the `Deref` bound is worth it. Additionally, there aren't clear conventions on when to bound and/or implement the `Deref` trait, so for now the conservative route is to require references instead of `U: Deref<T>`. To change this signature to using `Deref` would technically be a backwards-incompatible change, but it is doubtful that any code will actually break in practice.
This commit stabilizes the
clonediterator after tweaking the signature torequire that the iterator is over
&Tinstead ofU: Deref<T>. This method hashad time to bake for awhile now and it's not clear whether the
Derefbound isworth it. Additionally, there aren't clear conventions on when to bound and/or
implement the
Dereftrait, so for now the conservative route is to requirereferences instead of
U: Deref<T>.To change this signature to using
Derefwould technically be abackwards-incompatible change, but it is doubtful that any code will actually
break in practice.