Struct Spec 

pub struct Spec { /* private fields */ }

Spec describes a flag, in such a way that the parser can correctly identify it in the set of arguments given on the command-line.

Implementations

impl Spec

pub fn required( name: &str, help: &str, short_name: Option<char>, default_value: Option<&str>, ) -> Spec

Constructs a Spec which describes a required named flag. This flag may have a default value, but the key point is that it must have some value after parsing is complete.

pub fn optional(name: &str, help: &str, short_name: Option<char>) -> Spec

Constructs a Spec which describes an optional named flag. This flag may not have a value after we are finished parsing.

pub fn boolean(name: &str, help: &str, short_name: Option<char>) -> Spec

Constructs a Spec which describes a boolean named flag. Flags of this type always have a value, and that value is either true or false, instead of being a freeform string like other flag types.

If this flag is not specified at all on the command line, its “default value” is false.

pub fn positional( name: &str, help: &str, default_value: Option<&[&str]>, is_variadic: bool, ) -> Result<Spec>

Constructs a Spec which describes a positional flag. Flags of this type are not looked up by name after a “-” or “–” character, but instead are parsed purely by their position in the list of command-line arguments.

This also means that the order in which positional flags are added to a Specs structure matters for parsing.

A positional flag is variadic if it should be able to collect more than one value (e.g., for a command which takes a list of files to process of unspecified length).

pub fn get_name(&self) -> &str

Returns this flag’s full name (i.e., not the short name).

pub fn get_help(&self) -> &str

Returns the human-readable help text for this flag.

pub fn get_short_name(&self) -> Option<char>

Returns this flag’s short name, if it has one.

Trait Implementations

impl Clone for Spec

fn clone(&self) -> Spec

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Spec

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

Formats the value using the given formatter.