Enum ClickError 

#[non_exhaustive]
pub enum ClickError {
    UsageError {
        message: String,
        ctx: Option<Box<ErrorContext>>,
    },
    BadParameter {
        message: String,
        param_name: Option<String>,
        param_hint: Option<Vec<String>>,
        ctx: Option<Box<ErrorContext>>,
    },
    MissingParameter {
        message: Option<String>,
        param_name: Option<String>,
        param_hint: Option<Vec<String>>,
        param_type: ParamType,
        ctx: Option<Box<ErrorContext>>,
    },
    NoSuchOption {
        option_name: String,
        possibilities: Option<Vec<String>>,
        ctx: Option<Box<ErrorContext>>,
    },
    BadOptionUsage {
        option_name: String,
        message: String,
        ctx: Option<Box<ErrorContext>>,
    },
    BadArgumentUsage {
        message: String,
        ctx: Option<Box<ErrorContext>>,
    },
    FileError {
        filename: PathBuf,
        hint: String,
    },
    Abort,
    Exit {
        code: i32,
    },
}

The main error type for click-rs.

This enum represents all possible errors that can occur during CLI parsing and execution. It is marked #[non_exhaustive] to allow adding new variants in future versions without breaking compatibility.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

UsageError

A general usage error with the command.

This is the base error type for command usage problems. Exit code: 2

Fields

message: String

The error message

ctx: Option<Box<ErrorContext>>

Optional context for formatting

BadParameter

A parameter received an invalid value.

This error is raised when a callback or type conversion fails. Exit code: 2

Fields

message: String

The error message describing what went wrong

param_name: Option<String>

The name of the parameter (e.g., “–count” or “FILENAME”)

param_hint: Option<Vec<String>>

A hint to display instead of param_name (can be multiple values)

ctx: Option<Box<ErrorContext>>

Optional context for formatting

MissingParameter

A required parameter was not provided.

This error is raised when a required option or argument is missing. Exit code: 2

Fields

message: Option<String>

Optional additional message

param_name: Option<String>

The name of the missing parameter

param_hint: Option<Vec<String>>

A hint to display for the parameter

param_type: ParamType

The type of parameter (argument, option, or generic parameter)

ctx: Option<Box<ErrorContext>>

Optional context for formatting

NoSuchOption

An unknown option was provided.

This error includes possible corrections if similar options exist. Exit code: 2

Fields

option_name: String

The option name that was not recognized

possibilities: Option<Vec<String>>

Similar option names that might be what the user meant

ctx: Option<Box<ErrorContext>>

Optional context for formatting

BadOptionUsage

An option was used incorrectly.

For example, wrong number of arguments for an option. Exit code: 2

Fields

option_name: String

The option that was used incorrectly

message: String

The error message

ctx: Option<Box<ErrorContext>>

Optional context for formatting

BadArgumentUsage

An argument was used incorrectly.

For example, wrong number of values for an argument. Exit code: 2

Fields

message: String

The error message

ctx: Option<Box<ErrorContext>>

Optional context for formatting

FileError

A file operation failed.

Exit code: 1

Fields

filename: PathBuf

The path to the file that caused the error

hint: String

A description of what went wrong

Abort

The user aborted the operation.

This is typically raised when the user presses Ctrl+C or answers “no” to a confirmation prompt. Exit code: 1

Exit

Exit with a specific code.

This is used to signal that the application should exit with the given status code. A code of 0 indicates success.

Fields

code: i32

The exit code

Implementations

impl ClickError

pub fn exit_code(&self) -> i32

Get the exit code for this error.

Returns the appropriate exit code based on the error type:

• Exit: returns the specified code
• UsageError variants: returns 2
• Other errors: returns 1

pub fn format_message(&self) -> String

Format the error message for display to the user.

This method returns a user-friendly error message, potentially including usage information and help hints based on the error context.

pub fn format_full(&self) -> String

Format the complete error output including usage and help hints.

This method returns the full error output that should be shown to the user, including any usage information and “Try –help” hints.

pub fn is_usage_error(&self) -> bool

Check if this is a usage error (exit code 2).

pub fn context(&self) -> Option<&ErrorContext>

Get the error context, if any.

pub fn with_context(self, ctx: ErrorContext) -> Self

Attach context to this error.

This method consumes the error and returns a new error with the given context.

impl ClickError

pub fn usage(message: impl Into<String>) -> Self

Create a new usage error.

pub fn bad_parameter(message: impl Into<String>) -> Self

Create a new bad parameter error.

pub fn bad_parameter_named( message: impl Into<String>, param_name: impl Into<String>, ) -> Self

Create a new bad parameter error with a parameter name.

pub fn missing_option(name: impl Into<String>) -> Self

Create a new missing parameter error.

pub fn missing_argument(name: impl Into<String>) -> Self

Create a new missing argument error.

pub fn no_such_option(option_name: impl Into<String>) -> Self

Create a new “no such option” error.

pub fn no_such_option_with_suggestions( option_name: impl Into<String>, possibilities: Vec<String>, ) -> Self

Create a new “no such option” error with suggestions.

pub fn bad_option_usage( option_name: impl Into<String>, message: impl Into<String>, ) -> Self

Create a new bad option usage error.

pub fn bad_argument_usage(message: impl Into<String>) -> Self

Create a new bad argument usage error.

pub fn file_error(filename: impl Into<PathBuf>, hint: impl Into<String>) -> Self

Create a new file error.

pub fn abort() -> Self

Create an abort error.

pub fn exit(code: i32) -> Self

Create an exit error with the given code.

Trait Implementations

impl Debug for ClickError

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

Formats the value using the given formatter.

impl Display for ClickError

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

Formats the value using the given formatter.

impl Error for ClickError

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.