Struct Opt 

pub struct Opt { /* private fields */ }

Represents the result of parsing a single command-line option.

This structure contains information about a parsed option, including the option character, any error that occurred during parsing, and the option’s argument if one was provided.

Fields are private; use the val, erropt, arg, and into_arg accessors.

The argument is stored as a Cow<'static, str> so that borrowed inputs (string literals, &'static OsStr/&'static CStr from sources such as the argv crate) flow through without allocation when they don’t need to be sliced.

Implementations

impl Opt

pub fn val(&self) -> char

Returns the option character that was parsed.

This can be:

• The actual option character if it was valid
• ‘?’ if an unknown option was encountered
• ‘:’ if a missing argument was detected and optstring starts with ‘:’

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

Returns the error option character if an error occurred during parsing.

Returns:

• Some(char) containing the problematic option character if:
  • An unknown option was encountered
  • A required argument was missing
• None if no error occurred

pub fn arg(&self) -> Option<&str>

Returns the argument associated with the option, if any.

Returns:

• Some(&str) containing the option’s argument if one was provided
• None if the option takes no argument or if a required argument was missing

pub fn into_arg(self) -> Option<Cow<'static, str>>

Consumes self and returns the argument associated with the option, if any.

The returned Cow borrows from the original input when possible (e.g. when the argument was passed as a separate &'static str or valid-UTF-8 &'static OsStr), and only allocates when the parser had to slice into a larger argument (e.g. -ofile.txt).

Returns

• Some(Cow<'static, str>) containing the option’s argument if one was provided
• None if the option takes no argument or if a required argument was missing

Trait Implementations

impl Clone for Opt

fn clone(&self) -> Opt

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Opt

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

Formats the value using the given formatter.

impl PartialEq<char> for Opt

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialEq for Opt

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for Opt

impl StructuralPartialEq for Opt