Struct Error

pub struct Error<F: ErrorFormatter = DefaultFormatter> { /* private fields */ }

Command Line Argument Parser Error

See Command::error to create an error.

Implementations

impl<F: ErrorFormatter> Error<F>

pub fn raw(kind: ErrorKind, message: impl Display) -> Self

Create an unformatted error

This is for you need to pass the error up to a place that has access to the Command at which point you can call Error::format.

Prefer Command::error for generating errors.

pub fn format(self, cmd: &mut Command) -> Self

Format the existing message with the Command’s context

pub fn new(kind: ErrorKind) -> Self

Create an error with a pre-defined message

See also

• [Error::insert]
• Error::with_cmd

Example

let cmd = clap::Command::new("prog");

let mut err = clap::Error::new(ErrorKind::ValueValidation)
    .with_cmd(&cmd);
err.insert(ContextKind::InvalidArg, ContextValue::String("--foo".to_owned()));
err.insert(ContextKind::InvalidValue, ContextValue::String("bar".to_owned()));

err.print();

pub fn with_cmd(self, cmd: &Command) -> Self

Apply Command’s formatting to the error

Generally, this is used with Error::new

pub fn apply<EF: ErrorFormatter>(self) -> Error<EF>

Apply an alternative formatter to the error

Example

let cmd = Command::new("foo")
    .arg(Arg::new("input").required(true));
let matches = cmd
    .try_get_matches_from(["foo", "input.txt"])
    .map_err(|e| e.apply::<KindFormatter>())
    .unwrap_or_else(|e| e.exit());

pub fn kind(&self) -> ErrorKind

Type of error for programmatic processing

pub fn use_stderr(&self) -> bool

Should the message be written to stdout or not?

pub fn exit_code(&self) -> i32

Returns the exit code that .exit will exit the process with.

When the error’s kind would print to stderr this returns 2, else it returns 0.

pub fn exit(&self) -> !

Prints the error and exits.

Depending on the error kind, this either prints to stderr and exits with a status of 2 or prints to stdout and exits with a status of 0.

pub fn print(&self) -> Result<()>

Prints formatted and colored error to stdout or stderr according to its error kind

Example

use clap::Command;

match Command::new("Command").try_get_matches() {
    Ok(matches) => {
        // do_something
    },
    Err(err) => {
        err.print().expect("Error writing Error");
        // do_something
    },
};

pub fn render(&self) -> StyledStr

Render the error message to a StyledStr.

Example

use clap::Command;

match Command::new("Command").try_get_matches() {
    Ok(matches) => {
        // do_something
    },
    Err(err) => {
        let err = err.render();
        println!("{err}");
        // do_something
    },
};

Trait Implementations

impl<F: ErrorFormatter> Debug for Error<F>

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

Formats the value using the given formatter.

impl<F: ErrorFormatter> Display for Error<F>

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

Formats the value using the given formatter.

impl<F: ErrorFormatter> Error for Error<F>

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl<F: ErrorFormatter> From<Error> for Error<F>

fn from(e: Error) -> Self

Converts to this type from the input type.

impl<F: ErrorFormatter> From<Error> for Error<F>

fn from(e: Error) -> Self

Converts to this type from the input type.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 8 bytes