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impl ToSocketAddrs for String #39048
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(rust_highfive has picked a reviewer for you, use r? to override) |
Hm, this doesn't seem like a 'to' conversion, but an 'into' conversion. I'm trying to think if this would make it easy to accidentally write less efficient code, but I can't think how. |
Looks good to me, thanks! Impls like this are actually instantly stable so we just go ahead and tag them with a @rfcbot fcp merge |
Team member @alexcrichton has proposed to merge this. The next step is review by the rest of the tagged teams: No concerns currently listed. Once these reviewers reach consensus, this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up! See this document for info about what commands tagged team members can give me. |
@brson hm I'm not sure that there's any resources that the return value of |
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`ToSocketAddrs` is implemented for a number of different types, including `(IpAddr, u16)`, `&str`, and various others, for the convenience of being able to run things like `TcpListener::bind("10.11.12.13:1415")`. However, because this is a generic parameter with a trait bound, if you have a `String` you cannot pass it in, either directly as `TcpListener::bind(string)`, or the `TcpListener::bind(&string)` as you might expect due to deref coercion; you have to use `TcpListener::bind(&*string)`, which is noisy and hard to discover (though rust-lang#39029 suggests better error messages to make it more discoverable). Rather than making people stumble over this, just implement `ToSocketAddrs` for `String`.
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This is actually a "to" because it takes With this patch, any of the following should work (using
I don't think there are any performance implications, just one way that you might consume the string by accident which you can fix by inserting a single |
Also pushed new version with stability marked, as suggested by @alexcrichton. |
Hmm, this makes writing things like |
I found allowing passing of the ownership bad design at first. But then again, @alexcrichton had a good point about the DNS lookup dominating perf. Besides, if you are using a String that you don't need an ownership of in the future, the odds are that you've built that string for that occasion, for passing that into a function, and just have no use for it afterwards. If you have an use for it, unless you are a total newbie, you are going to prefer passing a reference over cloning it, and if you are a total newbie, that's not likely to be the most pressing problem in your code. So, after all, the downsides don't seem too dire, and it's an ergonomics win. |
It is possible to switch this to an impl on |
I share @llogiq's concern:
|
Consuming Which is more confusing? After considering the the fact that |
In this case, you'd be better off passing |
@tbu- this is more about helping Rust newcomers than pursuing elegance, as several others have pointed out. |
@xen0n I'm aware of that, and not opposed to adding a If we want such a change of string ideology, we should probably decide about that globally and not on a case-by-case basis, because it'll lead to an inconsistent standard library otherwise. E.g.: why does |
Comparison to |
I personally feel that helpful suggestions from the compiler are going to be more useful in the long run than clogging up std with impls for everything and the kitchen sink. |
ping @BurntSushi, @brson, @sfackler (checkboxes) |
After looking at it again I don't have any particular concerns, and it seems like most comments on thread are either pro or meh, not a lot of total opposition. |
🔔 This is now entering its final comment period, as per the review above. 🔔 |
@bors: r+ |
📌 Commit a5f2f36 has been approved by |
…ichton impl ToSocketAddrs for String `ToSocketAddrs` is implemented for a number of different types, including `(IpAddr, u16)`, `&str`, and various others, for the convenience of being able to run things like `TcpListener::bind("10.11.12.13:1415")`. However, because this is a generic parameter with a trait bound, if you have a `String` you cannot pass it in, either directly as `TcpListener::bind(string)`, or the `TcpListener::bind(&string)` as you might expect due to deref coercion; you have to use `TcpListener::bind(&*string)`, which is noisy and hard to discover (though #39029 suggests better error messages to make it more discoverable). Rather than making people stumble over this, just implement `ToSocketAddrs` for `String`.
☀️ Test successful - status-appveyor, status-travis |
Version 1.16.0 (2017-03-16) =========================== Language -------- * Lifetimes in statics and consts default to `'static`. [RFC 1623] * [The compiler's `dead_code` lint now accounts for type aliases][38051]. * [Uninhabitable enums (those without any variants) no longer permit wildcard match patterns][38069] * [Clean up semantics of `self` in an import list][38313] * [`Self` may appear in `impl` headers][38920] * [`Self` may appear in struct expressions][39282] Compiler -------- * [`rustc` now supports `--emit=metadata`, which causes rustc to emit a `.rmeta` file containing only crate metadata][38571]. This can be used by tools like the Rust Language Service to perform metadata-only builds. * [Levenshtein based typo suggestions now work in most places, while previously they worked only for fields and sometimes for local variables][38927]. Together with the overhaul of "no resolution"/"unexpected resolution" errors (#[38154]) they result in large and systematic improvement in resolution diagnostics. * [Fix `transmute::<T, U>` where `T` requires a bigger alignment than `U`][38670] * [rustc: use -Xlinker when specifying an rpath with ',' in it][38798] * [`rustc` no longer attempts to provide "consider using an explicit lifetime" suggestions][37057]. They were inaccurate. Stabilized APIs --------------- * [`VecDeque::truncate`] * [`VecDeque::resize`] * [`String::insert_str`] * [`Duration::checked_add`] * [`Duration::checked_sub`] * [`Duration::checked_div`] * [`Duration::checked_mul`] * [`str::replacen`] * [`str::repeat`] * [`SocketAddr::is_ipv4`] * [`SocketAddr::is_ipv6`] * [`IpAddr::is_ipv4`] * [`IpAddr::is_ipv6`] * [`Vec::dedup_by`] * [`Vec::dedup_by_key`] * [`Result::unwrap_or_default`] * [`<*const T>::wrapping_offset`] * [`<*mut T>::wrapping_offset`] * `CommandExt::creation_flags` * [`File::set_permissions`] * [`String::split_off`] Libraries --------- * [`[T]::binary_search` and `[T]::binary_search_by_key` now take their argument by `Borrow` parameter][37761] * [All public types in std implement `Debug`][38006] * [`IpAddr` implements `From<Ipv4Addr>` and `From<Ipv6Addr>`][38327] * [`Ipv6Addr` implements `From<[u16; 8]>`][38131] * [Ctrl-Z returns from `Stdin.read()` when reading from the console on Windows][38274] * [std: Fix partial writes in `LineWriter`][38062] * [std: Clamp max read/write sizes on Unix][38062] * [Use more specific panic message for `&str` slicing errors][38066] * [`TcpListener::set_only_v6` is deprecated][38304]. This functionality cannot be achieved in std currently. * [`writeln!`, like `println!`, now accepts a form with no string or formatting arguments, to just print a newline][38469] * [Implement `iter::Sum` and `iter::Product` for `Result`][38580] * [Reduce the size of static data in `std_unicode::tables`][38781] * [`char::EscapeDebug`, `EscapeDefault`, `EscapeUnicode`, `CaseMappingIter`, `ToLowercase`, `ToUppercase`, implement `Display`][38909] * [`Duration` implements `Sum`][38712] * [`String` implements `ToSocketAddrs`][39048] Cargo ----- * [The `cargo check` command does a type check of a project without building it][cargo/3296] * [crates.io will display CI badges from Travis and AppVeyor, if specified in Cargo.toml][cargo/3546] * [crates.io will display categories listed in Cargo.toml][cargo/3301] * [Compilation profiles accept integer values for `debug`, in addition to `true` and `false`. These are passed to `rustc` as the value to `-C debuginfo`][cargo/3534] * [Implement `cargo --version --verbose`][cargo/3604] * [All builds now output 'dep-info' build dependencies compatible with make and ninja][cargo/3557] * [Build all workspace members with `build --all`][cargo/3511] * [Document all workspace members with `doc --all`][cargo/3515] * [Path deps outside workspace are not members][cargo/3443] Misc ---- * [`rustdoc` has a `--sysroot` argument that, like `rustc`, specifies the path to the Rust implementation][38589] * [The `armv7-linux-androideabi` target no longer enables NEON extensions, per Google's ABI guide][38413] * [The stock standard library can be compiled for Redox OS][38401] * [Rust has initial SPARC support][38726]. Tier 3. No builds available. * [Rust has experimental support for Nvidia PTX][38559]. Tier 3. No builds available. * [Fix backtraces on i686-pc-windows-gnu by disabling FPO][39379] Compatibility Notes ------------------- * [Uninhabitable enums (those without any variants) no longer permit wildcard match patterns][38069] * In this release, references to uninhabited types can not be pattern-matched. This was accidentally allowed in 1.15. * [The compiler's `dead_code` lint now accounts for type aliases][38051]. * [Ctrl-Z returns from `Stdin.read()` when reading from the console on Windows][38274] * [Clean up semantics of `self` in an import list][38313] [37057]: rust-lang/rust#37057 [37761]: rust-lang/rust#37761 [38006]: rust-lang/rust#38006 [38051]: rust-lang/rust#38051 [38062]: rust-lang/rust#38062 [38062]: rust-lang/rust#38622 [38066]: rust-lang/rust#38066 [38069]: rust-lang/rust#38069 [38131]: rust-lang/rust#38131 [38154]: rust-lang/rust#38154 [38274]: rust-lang/rust#38274 [38304]: rust-lang/rust#38304 [38313]: rust-lang/rust#38313 [38314]: rust-lang/rust#38314 [38327]: rust-lang/rust#38327 [38401]: rust-lang/rust#38401 [38413]: rust-lang/rust#38413 [38469]: rust-lang/rust#38469 [38559]: rust-lang/rust#38559 [38571]: rust-lang/rust#38571 [38580]: rust-lang/rust#38580 [38589]: rust-lang/rust#38589 [38670]: rust-lang/rust#38670 [38712]: rust-lang/rust#38712 [38726]: rust-lang/rust#38726 [38781]: rust-lang/rust#38781 [38798]: rust-lang/rust#38798 [38909]: rust-lang/rust#38909 [38920]: rust-lang/rust#38920 [38927]: rust-lang/rust#38927 [39048]: rust-lang/rust#39048 [39282]: rust-lang/rust#39282 [39379]: rust-lang/rust#39379 [`<*const T>::wrapping_offset`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.wrapping_offset [`<*mut T>::wrapping_offset`]: https://doc.rust-lang.org/std/primitive.pointer.html#method.wrapping_offset [`Duration::checked_add`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.checked_add [`Duration::checked_div`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.checked_div [`Duration::checked_mul`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.checked_mul [`Duration::checked_sub`]: https://doc.rust-lang.org/std/time/struct.Duration.html#method.checked_sub [`File::set_permissions`]: https://doc.rust-lang.org/std/fs/struct.File.html#method.set_permissions [`IpAddr::is_ipv4`]: https://doc.rust-lang.org/std/net/enum.IpAddr.html#method.is_ipv4 [`IpAddr::is_ipv6`]: https://doc.rust-lang.org/std/net/enum.IpAddr.html#method.is_ipv6 [`Result::unwrap_or_default`]: https://doc.rust-lang.org/std/result/enum.Result.html#method.unwrap_or_default [`SocketAddr::is_ipv4`]: https://doc.rust-lang.org/std/net/enum.SocketAddr.html#method.is_ipv4 [`SocketAddr::is_ipv6`]: https://doc.rust-lang.org/std/net/enum.SocketAddr.html#method.is_ipv6 [`String::insert_str`]: https://doc.rust-lang.org/std/string/struct.String.html#method.insert_str [`String::split_off`]: https://doc.rust-lang.org/std/string/struct.String.html#method.split_off [`Vec::dedup_by_key`]: https://doc.rust-lang.org/std/vec/struct.Vec.html#method.dedup_by_key [`Vec::dedup_by`]: https://doc.rust-lang.org/std/vec/struct.Vec.html#method.dedup_by [`VecDeque::resize`]: https://doc.rust-lang.org/std/collections/vec_deque/struct.VecDeque.html#method.resize [`VecDeque::truncate`]: https://doc.rust-lang.org/std/collections/vec_deque/struct.VecDeque.html#method.truncate [`str::repeat`]: https://doc.rust-lang.org/std/primitive.str.html#method.repeat [`str::replacen`]: https://doc.rust-lang.org/std/primitive.str.html#method.replacen [cargo/3296]: rust-lang/cargo#3296 [cargo/3301]: rust-lang/cargo#3301 [cargo/3443]: rust-lang/cargo#3443 [cargo/3511]: rust-lang/cargo#3511 [cargo/3515]: rust-lang/cargo#3515 [cargo/3534]: rust-lang/cargo#3534 [cargo/3546]: rust-lang/cargo#3546 [cargo/3557]: rust-lang/cargo#3557 [cargo/3604]: rust-lang/cargo#3604 [RFC 1623]: https://github.com/rust-lang/rfcs/blob/master/text/1623-static.md
ToSocketAddrs
is implemented for a number of different types,including
(IpAddr, u16)
,&str
, and various others, for theconvenience of being able to run things like
TcpListener::bind("10.11.12.13:1415")
. However, because this is ageneric parameter with a trait bound, if you have a
String
you cannotpass it in, either directly as
TcpListener::bind(string)
, or theTcpListener::bind(&string)
as you might expect due to deref coercion;you have to use
TcpListener::bind(&*string)
, which is noisy and hardto discover (though #39029 suggests better error messages to make it
more discoverable).
Rather than making people stumble over this, just implement
ToSocketAddrs
forString
.