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Github Implement Extend and FromIterator for OsString by lopopolo · Pull Request...

 3 years ago
source link: https://github.com/rust-lang/rust/pull/82121
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lopopolo commented 28 days ago

Add the following trait impls:

  • impl Extend<OsString> for OsString
  • impl<'a> Extend<&'a OsStr> for OsString
  • impl FromIterator<OsString> for OsString
  • impl<'a> FromIterator<&'a OsStr> for OsString

Because OsString is a platform string with no particular semantics, concatenating them together seems acceptable.

I came across a use case for these trait impls in artichoke/artichoke#1089:

Artichoke is a Ruby interpreter. Its CLI accepts multiple -e switches for executing inline Ruby code, like:

$ cargo -q run --bin artichoke -- -e '2.times {' -e 'puts "foo: #{__LINE__}"' -e '}'
foo: 2
foo: 2

I use clap for command line argument parsing, which collects these -e commands into a Vec<OsString>. To pass these commands to the interpreter for Eval, I need to join them together. Combining these impls with Iterator::intersperse #79524 would enable me to build a single bit of Ruby code.

Currently, I'm doing something like:

let mut commands = commands.into_iter();
let mut buf = if let Some(command) = commands.next() {
    command
} else {
    return Ok(Ok(()));
};
for command in commands {
    buf.push("\n");
    buf.push(command);
}

If there's interest, I'd also like to add impls for Cow<'a, OsStr>, which would avoid allocating the "\n" OsString in the concatenate + intersperse use case.


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