Trait ArgAccess

pub trait ArgAccess<'arg>: Sized {
    // Required method
    fn take(self) -> Option<&'arg Arg>;
}

ArgAccess allows a visitor to decide if a given parameter needs an argument, based on the identity of the flag or option.

Consider --foo bar. Is this a pair of parameters (the flag --foo and the positional parameter bar) or a single option --foo bar that takes an argument? Similarly, -ab foo could be -a b, foo; or -a, -b foo; or -a, -b, foo. The ArgumentsParser can’t independently classify a given argument, so instead, a visitor can request an argument via this trait only for options that need them and the ArgumentParser takes care of the parsing logic of actually determining where that argument comes from.

Required Methods

fn take(self) -> Option<&'arg Arg>

Get an argument from the parser. This should only be called by options that need it; flags should simply ignore it, to ensure that the next command line argument can correctly be parsed independently.

This returns None if all of the CLI arguments have been exhausted, or if there are known to only be positional parameters remaining (because a raw -- was parsed at some point).

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors