#[non_exhaustive]
pub enum ArgAction {
Set,
Append,
StoreValue,
IncOccurrence,
SetTrue,
SetFalse,
Count,
Help,
Version,
}
Expand description
Behavior of arguments when they are encountered while parsing
Examples
let cmd = Command::new("mycmd")
.arg(
Arg::new("special-help")
.short('?')
.action(clap::ArgAction::Help)
);
// Existing help still exists
let err = cmd.clone().try_get_matches_from(["mycmd", "-h"]).unwrap_err();
assert_eq!(err.kind(), clap::error::ErrorKind::DisplayHelp);
// New help available
let err = cmd.try_get_matches_from(["mycmd", "-?"]).unwrap_err();
assert_eq!(err.kind(), clap::error::ErrorKind::DisplayHelp);
Variants (Non-exhaustive)
This enum is marked as non-exhaustive
Set
When encountered, store the associated value(s) in ArgMatches
Examples
let cmd = Command::new("mycmd")
.arg(
Arg::new("flag")
.long("flag")
.action(clap::ArgAction::Set)
);
let matches = cmd.try_get_matches_from(["mycmd", "--flag", "value"]).unwrap();
assert!(matches.contains_id("flag"));
assert_eq!(matches.occurrences_of("flag"), 0);
assert_eq!(
matches.get_many::<String>("flag").unwrap_or_default().map(|v| v.as_str()).collect::<Vec<_>>(),
vec!["value"]
);
Append
When encountered, store the associated value(s) in ArgMatches
Examples
let cmd = Command::new("mycmd")
.arg(
Arg::new("flag")
.long("flag")
.action(clap::ArgAction::Append)
);
let matches = cmd.try_get_matches_from(["mycmd", "--flag", "value1", "--flag", "value2"]).unwrap();
assert!(matches.contains_id("flag"));
assert_eq!(matches.occurrences_of("flag"), 0);
assert_eq!(
matches.get_many::<String>("flag").unwrap_or_default().map(|v| v.as_str()).collect::<Vec<_>>(),
vec!["value1", "value2"]
);
StoreValue
Deprecated, replaced with ArgAction::Set
or ArgAction::Append
IncOccurrence
Deprecated, replaced with ArgAction::SetTrue
or ArgAction::Count
SetTrue
When encountered, act as if "true"
was encountered on the command-line
If no default_value
is set, it will be false
.
No value is allowed. To optionally accept a value, see
Arg::default_missing_value
Examples
let cmd = Command::new("mycmd")
.arg(
Arg::new("flag")
.long("flag")
.action(clap::ArgAction::SetTrue)
);
let matches = cmd.clone().try_get_matches_from(["mycmd", "--flag", "--flag"]).unwrap();
assert!(matches.contains_id("flag"));
assert_eq!(matches.occurrences_of("flag"), 0);
assert_eq!(
matches.get_one::<bool>("flag").copied(),
Some(true)
);
let matches = cmd.try_get_matches_from(["mycmd"]).unwrap();
assert!(matches.contains_id("flag"));
assert_eq!(matches.occurrences_of("flag"), 0);
assert_eq!(
matches.get_one::<bool>("flag").copied(),
Some(false)
);
SetFalse
When encountered, act as if "false"
was encountered on the command-line
If no default_value
is set, it will be true
.
No value is allowed. To optionally accept a value, see
Arg::default_missing_value
Examples
let cmd = Command::new("mycmd")
.arg(
Arg::new("flag")
.long("flag")
.action(clap::ArgAction::SetFalse)
);
let matches = cmd.clone().try_get_matches_from(["mycmd", "--flag", "--flag"]).unwrap();
assert!(matches.contains_id("flag"));
assert_eq!(matches.occurrences_of("flag"), 0);
assert_eq!(
matches.get_one::<bool>("flag").copied(),
Some(false)
);
let matches = cmd.try_get_matches_from(["mycmd"]).unwrap();
assert!(matches.contains_id("flag"));
assert_eq!(matches.occurrences_of("flag"), 0);
assert_eq!(
matches.get_one::<bool>("flag").copied(),
Some(true)
);
Count
When encountered, increment a u8
counter
If no default_value
is set, it will be 0
.
No value is allowed. To optionally accept a value, see
Arg::default_missing_value
Examples
let cmd = Command::new("mycmd")
.arg(
Arg::new("flag")
.long("flag")
.action(clap::ArgAction::Count)
);
let matches = cmd.clone().try_get_matches_from(["mycmd", "--flag", "--flag"]).unwrap();
assert!(matches.contains_id("flag"));
assert_eq!(matches.occurrences_of("flag"), 0);
assert_eq!(
matches.get_one::<u8>("flag").copied(),
Some(2)
);
let matches = cmd.try_get_matches_from(["mycmd"]).unwrap();
assert!(matches.contains_id("flag"));
assert_eq!(matches.occurrences_of("flag"), 0);
assert_eq!(
matches.get_one::<u8>("flag").copied(),
Some(0)
);
Help
When encountered, display Command::print_help
Depending on the flag, Command::print_long_help
may be shown
Examples
let cmd = Command::new("mycmd")
.arg(
Arg::new("special-help")
.short('?')
.action(clap::ArgAction::Help)
);
// Existing help still exists
let err = cmd.clone().try_get_matches_from(["mycmd", "-h"]).unwrap_err();
assert_eq!(err.kind(), clap::error::ErrorKind::DisplayHelp);
// New help available
let err = cmd.try_get_matches_from(["mycmd", "-?"]).unwrap_err();
assert_eq!(err.kind(), clap::error::ErrorKind::DisplayHelp);
Version
When encountered, display Command::version
Depending on the flag, Command::long_version
may be shown
Examples
let cmd = Command::new("mycmd")
.version("1.0.0")
.arg(
Arg::new("special-version")
.long("special-version")
.action(clap::ArgAction::Version)
);
// Existing help still exists
let err = cmd.clone().try_get_matches_from(["mycmd", "--version"]).unwrap_err();
assert_eq!(err.kind(), clap::error::ErrorKind::DisplayVersion);
// New help available
let err = cmd.try_get_matches_from(["mycmd", "--special-version"]).unwrap_err();
assert_eq!(err.kind(), clap::error::ErrorKind::DisplayVersion);
Implementations
sourceimpl ArgAction
impl ArgAction
sourcepub fn takes_values(&self) -> bool
pub fn takes_values(&self) -> bool
Returns whether this action accepts values on the command-line
default_values
and [env
][super::Arg::env] may still be
processed.
Trait Implementations
Auto Trait Implementations
impl RefUnwindSafe for ArgAction
impl Send for ArgAction
impl Sync for ArgAction
impl Unpin for ArgAction
impl UnwindSafe for ArgAction
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
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.
sourcefn clone_into(&self, target: &mut T)
fn clone_into(&self, target: &mut T)
toowned_clone_into
)Uses borrowed data to replace owned data, usually by cloning. Read more