Trait clap::FromArgMatches

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

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

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

Derived as part of Parser, Args, and Subcommand.

Required Methods

fn from_arg_matches(matches: &ArgMatches) -> Result<Self, Error>

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"),
      }
  }
}

fn update_from_arg_matches(&mut self, matches: &ArgMatches) -> Result<(), Error>

Assign values from ArgMatches to self.

Provided Methods

fn from_arg_matches_mut(matches: &mut ArgMatches) -> Result<Self, Error>

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"),
      }
  }
}

fn update_from_arg_matches_mut( &mut self, matches: &mut ArgMatches ) -> Result<(), Error>

Assign values from ArgMatches to self.

Object Safety

This trait is not object safe.

Implementations on Foreign Types

impl<T: FromArgMatches> FromArgMatches for Box<T>

fn from_arg_matches(matches: &ArgMatches) -> Result<Self, Error>

fn from_arg_matches_mut(matches: &mut ArgMatches) -> Result<Self, Error>

fn update_from_arg_matches(&mut self, matches: &ArgMatches) -> Result<(), Error>

fn update_from_arg_matches_mut( &mut self, matches: &mut ArgMatches ) -> Result<(), Error>

Implementors