Struct ArgumentBuilder 

pub struct ArgumentBuilder { /* private fields */ }

Consuming builder for Argument.

Obtain via Argument::builder. Call ArgumentBuilder::build when done.

Examples

let arg = Argument::builder("format")
    .description("Output format")
    .default_value("text")
    .build()
    .unwrap();

assert_eq!(arg.default.as_deref(), Some("text"));
assert!(!arg.required);

Implementations

impl ArgumentBuilder

pub fn description(self, d: impl Into<String>) -> Self

Set the human-readable description for this argument.

pub fn required(self) -> Self

Mark this argument as required.

The parser will return crate::ParseError::MissingArgument if the argument is absent from the invocation.

pub fn default_value(self, d: impl Into<String>) -> Self

Set the default value used when this argument is not provided.

A default value is only meaningful for optional (non-required) arguments. If the argument is required and has a default, the default is still stored but the parser will still require the argument to be supplied.

pub fn variadic(self) -> Self

Mark this argument as variadic (consumes all remaining tokens).

A variadic argument must be the last argument defined on the command. crate::CommandBuilder::build enforces this constraint and returns crate::BuildError::VariadicNotLast if a variadic argument is followed by another argument.

pub fn build(self) -> Result<Argument, BuildError>

Consume the builder and return an Argument.

Errors

Returns BuildError::EmptyCanonical if the argument name is empty or consists entirely of whitespace.

Examples

assert!(Argument::builder("env").build().is_ok());
assert_eq!(Argument::builder("").build().unwrap_err(), BuildError::EmptyCanonical);