Trait clap::FromArgMatches

source · 
pub trait FromArgMatches: Sized {
    fn from_arg_matches(matches: &ArgMatches) -> Result<Self, Error>;
    fn update_from_arg_matches(
        &mut self,
        matches: &ArgMatches
    ) -> Result<(), Error>;

    fn from_arg_matches_mut(matches: &mut ArgMatches) -> Result<Self, Error> { ... }
    fn update_from_arg_matches_mut(
        &mut self,
        matches: &mut ArgMatches
    ) -> Result<(), Error> { ... }
}
Expand description

Converts an instance of ArgMatches to a user-defined container.

Derived as part of Parser, Args, and Subcommand.

Required Methods§

Instantiate Self from ArgMatches, parsing the arguments as needed.

Motivation: If our application had two CLI options, --name <STRING> and the flag --debug, we may create a struct as follows:

struct Context {
   name: String,
   debug: bool
}

We then need to convert the ArgMatches that clap generated into our struct. from_arg_matches serves as the equivalent of:

impl From<ArgMatches> for Context {
  fn from(m: ArgMatches) -> Self {
      Context {
          name: m.get_one::<String>("name").unwrap().clone(),
          debug: *m.get_one::<bool>("debug").expect("defaulted by clap"),
      }
  }
}

Assign values from ArgMatches to self.

Provided Methods§

Instantiate Self from ArgMatches, parsing the arguments as needed.

Motivation: If our application had two CLI options, --name <STRING> and the flag --debug, we may create a struct as follows:

struct Context {
   name: String,
   debug: bool
}

We then need to convert the ArgMatches that clap generated into our struct. from_arg_matches_mut serves as the equivalent of:

impl From<ArgMatches> for Context {
  fn from(m: ArgMatches) -> Self {
      Context {
          name: m.get_one::<String>("name").unwrap().to_string(),
          debug: *m.get_one::<bool>("debug").expect("defaulted by clap"),
      }
  }
}

Assign values from ArgMatches to self.

Implementations on Foreign Types§

Implementors§