Struct clap::error::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.

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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

See also

§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)>

Additional information to further qualify the error

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

Lookup a piece of context

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

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(&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
    },
};

Trait Implementations§

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

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

Formats the value using the given formatter. Read more
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impl<F: ErrorFormatter> Display for Error<F>

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

Formats the value using the given formatter. Read more
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impl<F: ErrorFormatter> Error for Error<F>

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

The lower-level source of this error, if any. Read more
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fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()
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fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting
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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. Read more
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impl<F: ErrorFormatter> From<Error> for Error<F>

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fn from(e: Error) -> Self

Converts to this type from the input type.
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impl<F: ErrorFormatter> From<Error> for Error<F>

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fn from(e: Error) -> Self

Converts to this type from the input type.

Auto Trait Implementations§

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impl<F = RichFormatter> !RefUnwindSafe for Error<F>

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impl<F> Send for Error<F>
where F: Send,

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impl<F> Sync for Error<F>
where F: Sync,

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impl<F> Unpin for Error<F>
where F: Unpin,

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impl<F = RichFormatter> !UnwindSafe for Error<F>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToString for T
where T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.