Struct Error

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

Expand description

Command Line Argument Parser Error

See Command::error to create an error.

Implementations§

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impl<F: ErrorFormatter> Error<F>

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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.

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

Format the existing message with the Command’s context

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pub fn new(kind: ErrorKind) -> Self

Create an error with a pre-defined message

§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();

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

Apply Command’s formatting to the error

Generally, this is used with Error::new

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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());

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pub fn kind(&self) -> ErrorKind

Type of error for programmatic processing

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pub fn context(&self) -> impl Iterator<Item = (ContextKind, &ContextValue)>

Available on crate feature error-context only.

Additional information to further qualify the error

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pub fn get(&self, kind: ContextKind) -> Option<&ContextValue>

Available on crate feature error-context only.

Lookup a piece of context

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pub fn insert( &mut self, kind: ContextKind, value: ContextValue, ) -> Option<ContextValue>

Available on crate feature error-context only.

Insert a piece of context

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pub fn use_stderr(&self) -> bool

Should the message be written to stdout or not?

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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.

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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.

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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
    },
};

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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
    },
};