Struct Arg

pub struct Arg<'a> {
    pub name: &'a str,
    pub short: Option<&'a str>,
    pub long: Option<&'a str>,
    pub about: &'a str,
    pub num_values: NumValues,
    pub value_name: Option<&'a str>,
    pub default: Option<fn() -> Value>,
    pub required: bool,
    pub value_type: Type,
    pub validation: fn(&Value) -> Result<(), String>,
}

Struct defining a single arg we can accept

Fields

name: &'a str

unique key (per Args) to identify this arg

short: Option<&'a str>

short (single dash, e.g -v) alias to match this arg with @note: if multiple args have the same “short” or “long” name then we have a race condition. We do not check for this but which we use should be considered undefined behaviour

long: Option<&'a str>

long (double dash, e.g –verbose) alias to match this arg with

about: &'a str

info about this arg, used when printing –help

num_values: NumValues

number of parameters this arg accepts. See NumValues for more details

value_name: Option<&'a str>

name for the value of this arg in –help, used when printing –help

default: Option<fn() -> Value>

default value for this arg if it is missing. By default no default is given

required: bool

whether this arg is required

value_type: Type

type for values, if given argparsing will fail if given the wrong type + Error::WrongValueType

validation: fn(&Value) -> Result<(), String>

additional validation for this arg. By default is a noop If this returns Err(String) argparsing will fail with the given string + Error::InvalidValue

Trait Implementations

impl<'a> Default for Arg<'a>

fn default() -> Self

Returns the “default value” for a type.