# Struct clap::ArgGroup

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    pub struct ArgGroup { /* private fields */ }

Expand description

Family of related arguments.

By placing arguments in a logical group, you can create easier requirement and exclusion rules instead of having to list each argument individually, or when you want a rule to apply “any but not all” arguments.

For instance, you can make an entire `ArgGroup` required. If `ArgGroup::multiple(true)` is set, this means that at least one argument from that group must be present. If `ArgGroup::multiple(false)` is set (the default), one and only one must be present.

You can also do things such as name an entire `ArgGroup` as a conflict or requirement for another argument, meaning any of the arguments that belong to that group will cause a failure if present, or must be present respectively.

Perhaps the most common use of `ArgGroup`s is to require one and only one argument to be present out of a given set. Imagine that you had multiple arguments, and you want one of them to be required, but making all of them required isn’t feasible because perhaps they conflict with each other. For example, lets say that you were building an application where one could set a given version number by supplying a string with an option argument, i.e. `--set-ver v1.2.3`, you also wanted to support automatically using a previous version number and simply incrementing one of the three numbers. So you create three flags `--major`, `--minor`, and `--patch`. All of these arguments shouldn’t be used at one time but you want to specify that at least one of them is used. For this, you can create a group.

Finally, you may use `ArgGroup`s to pull a value from a group of arguments when you don’t care exactly which argument was actually used at runtime.

## Examples

The following example demonstrates using an `ArgGroup` to ensure that one, and only one, of the arguments from the specified group is present at runtime.

    let result = Command::new("cmd")
        .arg(arg!(--"set-ver" <ver> "set the version manually"))
        .arg(arg!(--major           "auto increase major"))
        .arg(arg!(--minor           "auto increase minor"))
        .arg(arg!(--patch           "auto increase patch"))
        .group(ArgGroup::new("vers")
             .args(["set-ver", "major", "minor", "patch"])
             .required(true))
        .try_get_matches_from(vec!["cmd", "--major", "--patch"]);
    // Because we used two args in the group it's an error
    assert!(result.is_err());
    let err = result.unwrap_err();
    assert_eq!(err.kind(), ErrorKind::ArgumentConflict);

This next example shows a passing parse of the same scenario

    let result = Command::new("cmd")
        .arg(arg!(--"set-ver" <ver> "set the version manually"))
        .arg(arg!(--major           "auto increase major"))
        .arg(arg!(--minor           "auto increase minor"))
        .arg(arg!(--patch           "auto increase patch"))
        .group(ArgGroup::new("vers")
             .args(["set-ver", "major", "minor","patch"])
             .required(true))
        .try_get_matches_from(vec!["cmd", "--major"]);
    assert!(result.is_ok());
    let matches = result.unwrap();
    // We may not know which of the args was used, so we can test for the group...
    assert!(matches.contains_id("vers"));
    // We can also ask the group which arg was used
    assert_eq!(matches
        .get_one::<Id>("vers")
        .expect("`vers` is required")
        .as_str(),
        "major"
    );
    // we could also alternatively check each arg individually (not shown here)

## Implementations

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### impl ArgGroup

#### Builder

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#### pub fn new(id: impl Into<Id>) -> Self

Create a `ArgGroup` using a unique name.

The name will be used to get values from the group or refer to the group inside of conflict and requirement rules.

##### Examples

    ArgGroup::new("config")

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#### pub fn id(self, id: impl Into<Id>) -> Self

Sets the group name.

##### Examples

    ArgGroup::default().id("config")

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#### pub fn arg(self, arg_id: impl IntoResettable<Id>) -> Self

Adds an argument to this group by name

##### Examples

    let m = Command::new("myprog")
        .arg(Arg::new("flag")
            .short('f')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("color")
            .short('c')
            .action(ArgAction::SetTrue))
        .group(ArgGroup::new("req_flags")
            .arg("flag")
            .arg("color"))
        .get_matches_from(vec!["myprog", "-f"]);
    // maybe we don't know which of the two flags was used...
    assert!(m.contains_id("req_flags"));
    // but we can also check individually if needed
    assert!(m.contains_id("flag"));

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#### pub fn args(self, ns: impl IntoIterator<Item = impl Into<Id>>) -> Self

Adds multiple arguments to this group by name

##### Examples

    let m = Command::new("myprog")
        .arg(Arg::new("flag")
            .short('f')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("color")
            .short('c')
            .action(ArgAction::SetTrue))
        .group(ArgGroup::new("req_flags")
            .args(["flag", "color"]))
        .get_matches_from(vec!["myprog", "-f"]);
    // maybe we don't know which of the two flags was used...
    assert!(m.contains_id("req_flags"));
    // but we can also check individually if needed
    assert!(m.contains_id("flag"));

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#### pub fn get_args(&self) -> impl Iterator<Item = &Id>

Getters for all args. It will return a vector of `Id`

##### Example

    let args: Vec<&str> = vec!["a1".into(), "a4".into()];
    let grp = ArgGroup::new("program").args(&args);

    for (pos, arg) in grp.get_args().enumerate() {
        assert_eq!(*arg, args[pos]);
    }

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#### pub fn multiple(self, yes: bool) -> Self

Allows more than one of the `Arg`s in this group to be used. (Default: `false`)

##### Examples

Notice in this example we use both the `-f` and `-c` flags which are both part of the group

    let m = Command::new("myprog")
        .arg(Arg::new("flag")
            .short('f')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("color")
            .short('c')
            .action(ArgAction::SetTrue))
        .group(ArgGroup::new("req_flags")
            .args(["flag", "color"])
            .multiple(true))
        .get_matches_from(vec!["myprog", "-f", "-c"]);
    // maybe we don't know which of the two flags was used...
    assert!(m.contains_id("req_flags"));

In this next example, we show the default behavior (i.e. `multiple(false)) which will throw an error if more than one of the args in the group was used.

    let result = Command::new("myprog")
        .arg(Arg::new("flag")
            .short('f')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("color")
            .short('c')
            .action(ArgAction::SetTrue))
        .group(ArgGroup::new("req_flags")
            .args(["flag", "color"]))
        .try_get_matches_from(vec!["myprog", "-f", "-c"]);
    // Because we used both args in the group it's an error
    assert!(result.is_err());
    let err = result.unwrap_err();
    assert_eq!(err.kind(), ErrorKind::ArgumentConflict);

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#### pub fn is_multiple(&mut self) -> bool

Return true if the group allows more than one of the arguments in this group to be used. (Default: `false`)

##### Example

    let mut group = ArgGroup::new("myprog")
        .args(["f", "c"])
        .multiple(true);

    assert!(group.is_multiple());

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#### pub fn required(self, yes: bool) -> Self

Require an argument from the group to be present when parsing.

This is unless conflicting with another argument. A required group will be displayed in the usage string of the application in the format `<arg|arg2|arg3>`.

NOTE: This setting only applies to the current `Command` / `Subcommand`s, and not globally.

NOTE: By default, `ArgGroup::multiple` is set to `false` which when combined with `ArgGroup::required(true)` states, “One and only one arg must be used from this group. Use of more than one arg is an error.” Vice setting `ArgGroup::multiple(true)` which states, ’At least one arg from this group must be used. Using multiple is OK.“

##### Examples

    let result = Command::new("myprog")
        .arg(Arg::new("flag")
            .short('f')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("color")
            .short('c')
            .action(ArgAction::SetTrue))
        .group(ArgGroup::new("req_flags")
            .args(["flag", "color"])
            .required(true))
        .try_get_matches_from(vec!["myprog"]);
    // Because we didn't use any of the args in the group, it's an error
    assert!(result.is_err());
    let err = result.unwrap_err();
    assert_eq!(err.kind(), ErrorKind::MissingRequiredArgument);

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#### pub fn requires(self, id: impl IntoResettable<Id>) -> Self

Specify an argument or group that must be present when this group is.

This is not to be confused with a required group. Requirement rules function just like argument requirement rules, you can name other arguments or groups that must be present when any one of the arguments from this group is used.

NOTE: The name provided may be an argument or group name

##### Examples

    let result = Command::new("myprog")
        .arg(Arg::new("flag")
            .short('f')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("color")
            .short('c')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("debug")
            .short('d')
            .action(ArgAction::SetTrue))
        .group(ArgGroup::new("req_flags")
            .args(["flag", "color"])
            .requires("debug"))
        .try_get_matches_from(vec!["myprog", "-c"]);
    // because we used an arg from the group, and the group requires "-d" to be used, it's an
    // error
    assert!(result.is_err());
    let err = result.unwrap_err();
    assert_eq!(err.kind(), ErrorKind::MissingRequiredArgument);

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#### pub fn requires_all(self, ns: impl IntoIterator<Item = impl Into<Id>>) -> Self

Specify arguments or groups that must be present when this group is.

This is not to be confused with a required group. Requirement rules function just like argument requirement rules, you can name other arguments or groups that must be present when one of the arguments from this group is used.

NOTE: The names provided may be an argument or group name

##### Examples

    let result = Command::new("myprog")
        .arg(Arg::new("flag")
            .short('f')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("color")
            .short('c')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("debug")
            .short('d')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("verb")
            .short('v')
            .action(ArgAction::SetTrue))
        .group(ArgGroup::new("req_flags")
            .args(["flag", "color"])
            .requires_all(["debug", "verb"]))
        .try_get_matches_from(vec!["myprog", "-c", "-d"]);
    // because we used an arg from the group, and the group requires "-d" and "-v" to be used,
    // yet we only used "-d" it's an error
    assert!(result.is_err());
    let err = result.unwrap_err();
    assert_eq!(err.kind(), ErrorKind::MissingRequiredArgument);

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#### pub fn conflicts_with(self, id: impl IntoResettable<Id>) -> Self

Specify an argument or group that must not be present when this group is.

Exclusion (aka conflict) rules function just like argument exclusion rules, you can name other arguments or groups that must not be present when one of the arguments from this group are used.

NOTE: The name provided may be an argument, or group name

##### Examples

    let result = Command::new("myprog")
        .arg(Arg::new("flag")
            .short('f')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("color")
            .short('c')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("debug")
            .short('d')
            .action(ArgAction::SetTrue))
        .group(ArgGroup::new("req_flags")
            .args(["flag", "color"])
            .conflicts_with("debug"))
        .try_get_matches_from(vec!["myprog", "-c", "-d"]);
    // because we used an arg from the group, and the group conflicts with "-d", it's an error
    assert!(result.is_err());
    let err = result.unwrap_err();
    assert_eq!(err.kind(), ErrorKind::ArgumentConflict);

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#### pub fn conflicts_with_all(
self,
ns: impl IntoIterator<Item = impl Into<Id>>
) -> Self

Specify arguments or groups that must not be present when this group is.

Exclusion rules function just like argument exclusion rules, you can name other arguments or groups that must not be present when one of the arguments from this group are used.

NOTE: The names provided may be an argument, or group name

##### Examples

    let result = Command::new("myprog")
        .arg(Arg::new("flag")
            .short('f')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("color")
            .short('c')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("debug")
            .short('d')
            .action(ArgAction::SetTrue))
        .arg(Arg::new("verb")
            .short('v')
            .action(ArgAction::SetTrue))
        .group(ArgGroup::new("req_flags")
            .args(["flag", "color"])
            .conflicts_with_all(["debug", "verb"]))
        .try_get_matches_from(vec!["myprog", "-c", "-v"]);
    // because we used an arg from the group, and the group conflicts with either "-v" or "-d"
    // it's an error
    assert!(result.is_err());
    let err = result.unwrap_err();
    assert_eq!(err.kind(), ErrorKind::ArgumentConflict);

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### impl ArgGroup

#### Reflection

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#### pub fn get_id(&self) -> &Id

Get the name of the group

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#### pub fn is_required_set(&self) -> bool

Reports whether `ArgGroup::required` is set

## Trait Implementations

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### impl Clone for ArgGroup

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#### fn clone(&self) -> ArgGroup

Returns a copy of the value. Read more

1.0.0 · source

#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more

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### impl Debug for ArgGroup

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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 Default for ArgGroup

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#### fn default() -> ArgGroup

Returns the “default value” for a type. Read more

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### impl From<&ArgGroup> for ArgGroup

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#### fn from(g: &ArgGroup) -> Self

Converts to this type from the input type.

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### impl PartialEq<ArgGroup> for ArgGroup

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#### fn eq(&self, other: &ArgGroup) -> bool

This method tests for `self` and `other` values to be equal, and is used by `==`. Read more

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#### fn ne(&self, other: &ArgGroup) -> bool

This method tests for `!=`.

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### impl Eq for ArgGroup

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### impl StructuralEq for ArgGroup

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### impl StructuralPartialEq for ArgGroup

## Auto Trait Implementations

### impl RefUnwindSafe for ArgGroup

### impl Send for ArgGroup

### impl Sync for ArgGroup

### impl Unpin for ArgGroup

### impl UnwindSafe for ArgGroup

## 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,

const: unstable · source

#### 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,

const: unstable · source

#### 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

const: unstable · source

#### fn from(t: T) -> T

Returns the argument unchanged.

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

const: unstable · source

#### 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> ToOwned for T where
T: Clone,

#### type Owned = T

The resulting type after obtaining ownership.

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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more

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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more

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### impl<T, U> TryFrom<U> for T where
U: Into<T>,

#### type Error = Infallible

The type returned in the event of a conversion error.

const: unstable · source

#### 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>,

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

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.