Struct ap::Arg

pub struct Arg {
    pub option: char,
    pub needs: Need,
    pub help: Option<String>,
    pub required: bool,
    pub value: Option<String>,
    pub count: usize,
}

An argument, either an option or a positional argument.

1. It is used to specify how an argument is to be handled.

   If it is to be considered an option, the [Arg.option] member should be set.

2. To store the results of the parse for the argument.

   For example, the parser records the number of times the argument was handled in the count member.

Note

• All members are public for handler convenience.

Fields

option: char

Single character short option name (required). Can be set to special values for non-standard behaviour:

• POSITIONAL_HANDLER_OPT (to handle positional arguments).
• UNKNOWN_OPTION_HANDLER_OPT (to handle unknown options).

needs: Need

Type of option (required, but defaults).

help: Option<String>

Description of the option.

required: bool

Set if the option must be specified.

value: Option<String>

Value specified for this option (if the needs member is not Need::Nothing).

Notes

• This is equivalent to getopt(3)’s optarg value.
• This will be None for flag options.

count: usize

Number of times the option was specified.

Notes

• Used internally for Error::MissingReqOpt.
• If a positional argument handler has been registered, value will be incremented for each positional argument specified.
• This is similar to getopt(3)’s optind value, but rather than being the overall index, it is a value incremented each time the particular option is specified on the command-line.

Implementations

impl Arg

pub fn new(option: char) -> Self

Create a new argument handler.

pub fn option(self, option: char) -> Self

Specify the option character (name) for the option.

pub fn needs(self, needs: Need) -> Self

Specify the requirement for the option.

pub fn help(self, help: &str) -> Self

Specify the help text for the option.

pub fn required(self) -> Self

Specify that the option must be provided on the command-line.

Trait Implementations

impl Clone for Arg

fn clone(&self) -> Arg

Returns a copy of the value.

pub fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Arg

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Arg

fn default() -> Arg

Returns the “default value” for a type.

impl Display for Arg

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for Arg

impl Ord for Arg

fn cmp(&self, other: &Arg) -> Ordering

This method returns an Ordering between self and other.

#[must_use]

pub fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]

pub fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]

pub fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl PartialEq<Arg> for Arg

fn eq(&self, other: &Arg) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Arg) -> bool

This method tests for !=.

impl PartialOrd<Arg> for Arg

fn partial_cmp(&self, other: &Arg) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

#[must_use]

pub fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

#[must_use]

pub fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

#[must_use]

pub fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

#[must_use]

pub fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralEq for Arg

impl StructuralPartialEq for Arg