pub enum ErrorKind {
Show 20 variants
InvalidValue,
UnknownArgument,
InvalidSubcommand,
UnrecognizedSubcommand,
EmptyValue,
ValueValidation,
TooManyValues,
TooFewValues,
WrongNumberOfValues,
ArgumentConflict,
MissingRequiredArgument,
MissingSubcommand,
MissingArgumentOrSubcommand,
UnexpectedMultipleUsage,
InvalidUtf8,
HelpDisplayed,
VersionDisplayed,
ArgumentNotFound,
Io,
Format,
}
Expand description
Command line argument parser kind of error
Variants
InvalidValue
Occurs when an Arg
has a set of possible values,
and the user provides a value which isn’t in that set.
Examples
let result = App::new("prog")
.arg(Arg::with_name("speed")
.possible_value("fast")
.possible_value("slow"))
.get_matches_from_safe(vec!["prog", "other"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::InvalidValue);
UnknownArgument
Occurs when a user provides a flag, option, argument or subcommand which isn’t defined.
Examples
let result = App::new("prog")
.arg(Arg::from_usage("--flag 'some flag'"))
.get_matches_from_safe(vec!["prog", "--other"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::UnknownArgument);
InvalidSubcommand
Occurs when the user provides an unrecognized SubCommand
which meets the threshold for
being similar enough to an existing subcommand.
If it doesn’t meet the threshold, or the ‘suggestions’ feature is disabled,
the more general UnknownArgument
error is returned.
Examples
let result = App::new("prog")
.subcommand(SubCommand::with_name("config")
.about("Used for configuration")
.arg(Arg::with_name("config_file")
.help("The configuration file to use")
.index(1)))
.get_matches_from_safe(vec!["prog", "confi"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::InvalidSubcommand);
UnrecognizedSubcommand
Occurs when the user provides an unrecognized SubCommand
which either
doesn’t meet the threshold for being similar enough to an existing subcommand,
or the ‘suggestions’ feature is disabled.
Otherwise the more detailed InvalidSubcommand
error is returned.
This error typically happens when passing additional subcommand names to the help
subcommand. Otherwise, the more general UnknownArgument
error is used.
Examples
let result = App::new("prog")
.subcommand(SubCommand::with_name("config")
.about("Used for configuration")
.arg(Arg::with_name("config_file")
.help("The configuration file to use")
.index(1)))
.get_matches_from_safe(vec!["prog", "help", "nothing"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::UnrecognizedSubcommand);
EmptyValue
Occurs when the user provides an empty value for an option that does not allow empty values.
Examples
let res = App::new("prog")
.arg(Arg::with_name("color")
.long("color")
.empty_values(false))
.get_matches_from_safe(vec!["prog", "--color="]);
assert!(res.is_err());
assert_eq!(res.unwrap_err().kind, ErrorKind::EmptyValue);
ValueValidation
Occurs when the user provides a value for an argument with a custom validation and the value fails that validation.
Examples
fn is_numeric(val: String) -> Result<(), String> {
match val.parse::<i64>() {
Ok(..) => Ok(()),
Err(..) => Err(String::from("Value wasn't a number!")),
}
}
let result = App::new("prog")
.arg(Arg::with_name("num")
.validator(is_numeric))
.get_matches_from_safe(vec!["prog", "NotANumber"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::ValueValidation);
TooManyValues
Occurs when a user provides more values for an argument than were defined by setting
Arg::max_values
.
Examples
let result = App::new("prog")
.arg(Arg::with_name("arg")
.multiple(true)
.max_values(2))
.get_matches_from_safe(vec!["prog", "too", "many", "values"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::TooManyValues);
TooFewValues
Occurs when the user provides fewer values for an argument than were defined by setting
Arg::min_values
.
Examples
let result = App::new("prog")
.arg(Arg::with_name("some_opt")
.long("opt")
.min_values(3))
.get_matches_from_safe(vec!["prog", "--opt", "too", "few"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::TooFewValues);
WrongNumberOfValues
Occurs when the user provides a different number of values for an argument than what’s
been defined by setting Arg::number_of_values
or than was implicitly set by
Arg::value_names
.
Examples
let result = App::new("prog")
.arg(Arg::with_name("some_opt")
.long("opt")
.takes_value(true)
.number_of_values(2))
.get_matches_from_safe(vec!["prog", "--opt", "wrong"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::WrongNumberOfValues);
ArgumentConflict
Occurs when the user provides two values which conflict with each other and can’t be used together.
Examples
let result = App::new("prog")
.arg(Arg::with_name("debug")
.long("debug")
.conflicts_with("color"))
.arg(Arg::with_name("color")
.long("color"))
.get_matches_from_safe(vec!["prog", "--debug", "--color"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::ArgumentConflict);
MissingRequiredArgument
Occurs when the user does not provide one or more required arguments.
Examples
let result = App::new("prog")
.arg(Arg::with_name("debug")
.required(true))
.get_matches_from_safe(vec!["prog"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::MissingRequiredArgument);
MissingSubcommand
Occurs when a subcommand is required (as defined by AppSettings::SubcommandRequired
),
but the user does not provide one.
Examples
let err = App::new("prog")
.setting(AppSettings::SubcommandRequired)
.subcommand(SubCommand::with_name("test"))
.get_matches_from_safe(vec![
"myprog",
]);
assert!(err.is_err());
assert_eq!(err.unwrap_err().kind, ErrorKind::MissingSubcommand);
MissingArgumentOrSubcommand
Occurs when either an argument or SubCommand
is required, as defined by
AppSettings::ArgRequiredElseHelp
, but the user did not provide one.
Examples
let result = App::new("prog")
.setting(AppSettings::ArgRequiredElseHelp)
.subcommand(SubCommand::with_name("config")
.about("Used for configuration")
.arg(Arg::with_name("config_file")
.help("The configuration file to use")))
.get_matches_from_safe(vec!["prog"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::MissingArgumentOrSubcommand);
UnexpectedMultipleUsage
Occurs when the user provides multiple values to an argument which doesn’t allow that.
Examples
let result = App::new("prog")
.arg(Arg::with_name("debug")
.long("debug")
.multiple(false))
.get_matches_from_safe(vec!["prog", "--debug", "--debug"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::UnexpectedMultipleUsage);
InvalidUtf8
Occurs when the user provides a value containing invalid UTF-8 for an argument and
AppSettings::StrictUtf8
is set.
Platform Specific
Non-Windows platforms only (such as Linux, Unix, macOS, etc.)
Examples
let result = App::new("prog")
.setting(AppSettings::StrictUtf8)
.arg(Arg::with_name("utf8")
.short("u")
.takes_value(true))
.get_matches_from_safe(vec![OsString::from("myprog"),
OsString::from("-u"),
OsString::from_vec(vec![0xE9])]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::InvalidUtf8);
HelpDisplayed
Not a true “error” as it means --help
or similar was used.
The help message will be sent to stdout
.
Note: If the help is displayed due to an error (such as missing subcommands) it will
be sent to stderr
instead of stdout
.
Examples
let result = App::new("prog")
.get_matches_from_safe(vec!["prog", "--help"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::HelpDisplayed);
VersionDisplayed
Not a true “error” as it means --version
or similar was used.
The message will be sent to stdout
.
Examples
let result = App::new("prog")
.get_matches_from_safe(vec!["prog", "--version"]);
assert!(result.is_err());
assert_eq!(result.unwrap_err().kind, ErrorKind::VersionDisplayed);
ArgumentNotFound
Occurs when using the value_t!
and values_t!
macros to convert an argument value
into type T
, but the argument you requested wasn’t used. I.e. you asked for an argument
with name config
to be converted, but config
wasn’t used by the user.
value_t!
: ./macro.value_t!.html
values_t!
: ./macro.values_t!.html
Io
Represents an [I/O error].
Can occur when writing to stderr
or stdout
or reading a configuration file.
[I/O error]: https://doc.rust-lang.org/std/io/struct.Error.html
Format
Represents a Format error (which is a part of Display
).
Typically caused by writing to stderr
or stdout
.
Trait Implementations
impl Copy for ErrorKind
impl StructuralPartialEq for ErrorKind
Auto Trait Implementations
impl RefUnwindSafe for ErrorKind
impl Send for ErrorKind
impl Sync for ErrorKind
impl Unpin for ErrorKind
impl UnwindSafe for ErrorKind
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcepub fn borrow_mut(&mut self) -> &mut T
pub fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> ToOwned for T where
T: Clone,
impl<T> ToOwned for T where
T: Clone,
type Owned = T
type Owned = T
The resulting type after obtaining ownership.
sourcepub fn to_owned(&self) -> T
pub fn to_owned(&self) -> T
Creates owned data from borrowed data, usually by cloning. Read more
sourcepub fn clone_into(&self, target: &mut T)
pub fn clone_into(&self, target: &mut T)
toowned_clone_into
)Uses borrowed data to replace owned data, usually by cloning. Read more