Commits on Jul 13, 2021

1. imp: Make clap_derive call FromStr::from_str only once per argument. …

   Currently the way `clap_derive` uses a `from_str` function is to call
   it once as a validator, discarding the parsed value, and then to call
   it again to recompute the parsed value. This is unfortunate in
   cases where `from_str` is expensive or has side effects.
   
   This PR changes `clap_derive` to not register `from_str` as a validator
   so that it doesn't do the first of these two calls. Then, instead of
   doing `unwrap()` on the other call, it handles the error. This eliminates
   the redundancy, and also avoids the small performance hit mentioned in
   [the documentation about validators].
   
   [the documentation about validators]: https://docs.rs/clap-v3/3.0.0-beta.1/clap_v3/struct.Arg.html#method.validator
   
   This PR doesn't yet use colorized messages for errors generated during
   parsing because the `ColorWhen` setting isn't currently available.
   That's fixable with some refactoring, but I'm interested in getting
   feedback on the overall approach here first.

   

   sunfishcode committed Jul 13, 2021
   Configuration menu

   • View commit details
   • Copy full SHA for db8c060
   • Browse repository at this point

   Copy the full SHA

   db8c060 View commit details

   Browse the repository at this point in the history