Add unstable Iterator::copied()
Initially suggested at https://github.com/bluss/rust-itertools/pull/289, however the maintainers of itertools suggested this may be better of in a standard library.
The intent of `copied` is to avoid accidentally cloning iterator elements after doing a code refactoring which causes a structure to be no longer `Copy`. This is a relatively common pattern, as it can be seen by calling `rg --pcre2 '[.]map[(][|](?:(\w+)[|] [*]\1|&(\w+)[|] \2)[)]'` on Rust main repository. Additionally, many uses of `cloned` actually want to simply `Copy`, and changing something to be no longer copyable may introduce unnoticeable performance penalty.
Also, this makes sense because the standard library includes `[T].copy_from_slice` to pair with `[T].clone_from_slice`.
This also adds `Option::copied`, because it makes sense to pair it with `Iterator::copied`. I don't think this feature is particularly important, but it makes sense to update `Option` along with `Iterator` for consistency.
Pin stabilization
This implements the changes suggested in https://github.com/rust-lang/rust/issues/55766#issue-378417538 and stabilizes the `pin` feature. @alexcrichton also listed several "blockers" in that issue, but then in [this comment](https://github.com/rust-lang/rust/issues/55766#issuecomment-445074980) mentioned that they're more "TODO items":
> In that vein I think it's fine for a stabilization PR to be posted at any time now with FCP lapsed for a week or so now. The final points about self/pin/pinned can be briefly discussed there (if even necessary, they could be left as the proposal above).
Let's settle these last bits here and get this thing stabilized! :)
r? @alexcrichton
cc @withoutboats
Changes the original example to use more idiomatic formatting as well
as `.checked_add`. Also adds a second example to show a case where the
`.collect` returns `None`.
Remove pin::Unpin reexport and add Unpin to the prelude.
Change Pin associated functions to methods.
Rename get_mut_unchecked_ to get_unchecked_mut
Remove impl Unpin for Pin
Mark Pin repr(transparent)
Update to a new pinning API.
~~Blocked on #53843 because of method resolution problems with new pin type.~~
@r? @cramertj
cc @RalfJung @pythonesque anyone interested in #49150
Add a implementation of `From` for converting `&'a Option<T>` into `Option<&'a T>`
I'm not sure if any annotations regarding the stabilization are needed or in general what's the correct process of adding such an impl.
cc @sgrif (We have talked about this)
Amend option.take examples
It wasn't abundantly clear to me what `.take` returned. Perhaps this is a slightly frivolous change, but I think it's an improvement. =)
Apologies if I'm not following proper procedures.
It wasn't abundantly clear to me what `.take` returned. Perhaps this is a slightly frivolous change, but I think it's an improvement. =)
Apologies if I'm not following proper procedures.
New safe associated functions for PinMut
- Add safe `get_mut` and `map`
- Rename unsafe equivalents to `get_mut_unchecked` and `map_unchecked`
The discussion about this starts [in this comment](https://github.com/rust-lang/rust/issues/49150#issuecomment-399604573) on the tracking issue.
FusedIterator is a marker trait that promises that the implementing
iterator continues to return `None` from `.next()` once it has returned
`None` once (and/or `.next_back()`, if implemented).
The effects of FusedIterator are already widely available through
`.fuse()`, but with stable `FusedIterator`, stable Rust users can
implement this trait for their iterators when appropriate.
A user in a reddit thread was confused by the name of the variable
"num_as_int"; they thought the example was trying to convert the
string "10" as if it were binary 2 by calling str::len(). In reality,
the example is simply demonstrating how to take an immutable reference
to the value of an Option. The confusion comes from the coincidence
that the length of the string "10" is also its binary representation,
and the implication from the variable names that a conversion was
occuring ("num_as_str" to "num_as_int").
This PR changes the example number to 12 instead of 10, and changes
the variable name from "num_as_int" to "num_length" to better
communicate what the example is doing.
The reddit thread:
https://www.reddit.com/r/rust/comments/7zpvev/notyetawesome_rust_what_use_cases_would_you_like/dur39xw/
Add transpose conversions for nested Option and Result
These impls are useful when working with combinator
methods that expect an option or a result, but you
have a `Result<Option<T>, E>` instead of an `Option<Result<T, E>>`
or vice versa.
These impls are useful when working with combinator
methods that expect an option or a result, but you
have a Result<Option<T>, E> instead of an Option<Result<T, E>>
or vice versa.
