Implemented Extend<String> and FromIterator<String> for String. #27956
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It's somewhat unfortunate that these impls have to be insta-stable, but I'm ok with these. I'll bring this up during the libs triage meeting to make sure we're all on board though. |
alexcrichton
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Does this have to be insta-stable because its an impl of a stable trait for a stable type or for another reason? |
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The stability checking system doesn't consider the stability of trait implementations that are used at the moment. |
| fn extend<I: IntoIterator<Item=String>>(&mut self, iterable: I) { | ||
| let iterator = iterable.into_iter(); | ||
| let (lower_bound, _) = iterator.size_hint(); | ||
| self.reserve(lower_bound); |
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Does the observation from #27986 apply here, too? (i.e. the strings from the iterator might be empty, hence it is better to keep the code simpler and trust the reallocation strategy)
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Yes it does, thanks. I was surprised by that code, but thought "when in Rome". If the libs team approves this PR I'll remove that and rebase.
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We discussed this at the libs team meeting today and decided this was ok to merge, but I'm going to run crater beforehand to be super sure that there were no accidental regressions. |
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Adjusted implementation of Extend per @ranma42; should be ready to merge if the crater run is okay. |
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Crater reports zero regressions, so this is good to go on that front. |
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| #[stable(feature = "extend_string", since = "1.4.0")] | ||
| impl FromIterator<String> for String> { |
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Looks like the travis builds are failing due to a syntax error on this line.
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fixed typo (sorry I didn't catch this in a local test, some issue with jemalloc was blocking compiling liballoc & I just didn't deal with it) |
If you have an `Iterator<Item=String>` (say because those items were generated using `.to_string()` or similarly), borrow semantics do not permit you map that to an `Iterator<&'a str>`. These two implementations close a small gap in the `String` API. At the same time I've also made the names of the parameters to `String`'s `Extend` and `FromIterator` implementations consistent.
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If you have an
Iterator<Item=String>(say because those items were generated using.to_string()or similarly), borrow semantics do not permit you map that to anIterator<&'a str>. These two implementations close a small gap in theStringAPI.At the same time I've also made the names of the parameters to
String'sExtendandFromIteratorimplementations consistent.