diff --git a/src/args/arg.rs b/src/args/arg.rs index a2edbd5a9aa..5d8e077429c 100644 --- a/src/args/arg.rs +++ b/src/args/arg.rs @@ -1891,11 +1891,11 @@ impl<'a, 'b> Arg<'a, 'b> { /// **WARNING:** /// /// Setting `multiple(true)` for an [option] with no other details, allows multiple values - /// **and** multiple occurrences because it isn't possible to have more occurrences than values for - /// options. Because multiple values are allowed, `--option val1 val2 val3` is perfectly valid, - /// be careful when designing a CLI where positional arguments are expected after a option which - /// accepts multiple values, as `clap` will continue parsing *values* until it reaches the max - /// or specific number of values defined, or another flag or option. + /// **and** multiple occurrences because it isn't possible to have more occurrences than values + /// for options. Because multiple values are allowed, `--option val1 val2 val3` is perfectly + /// valid, be careful when designing a CLI where positional arguments are expected after a + /// option which accepts multiple values, as `clap` will continue parsing *values* until it + /// reaches the max or specific number of values defined, or another flag or option. /// /// **Pro Tip**: /// @@ -1903,6 +1903,36 @@ impl<'a, 'b> Arg<'a, 'b> { /// occurrence. To do this use [`Arg::number_of_values(1)`] in coordination with /// [`Arg::multiple(true)`]. /// + /// **WARNING:** + /// + /// When using args with `multiple(true)` on [options] or [positionals] (i.e. those args that + /// accept values) and [subcommands], one needs to consider the posibility of an argument value + /// being the same as a valid subcommand. By default `clap` will parse the argument in question + /// as a value *only if* a value is possible at that moment. Otherwise it will be parsed as a + /// subcommand. In effect, this means using `multiple(true)` with no additional parameters and + /// a possible value that coincides with a subcommand name, the subcommand cannot be called + /// unless another argument is passed first. + /// + /// As an example, consider a CLI with an option `--ui-paths=...` and subcommand `signer` + /// + /// The following would be parsed as values to `--ui-paths`. + /// + /// ```notrust + /// $ program --ui-paths path1 path2 signer + /// ``` + /// + /// This is because `--ui-paths` accepts multiple values. `clap` will continue parsing values + /// until another argument is reached and it knows `--ui-paths` is done. + /// + /// By adding additional parameters to `--ui-paths` we can solve this issue. Consider adding + /// [`Arg::number_of_values(1)`] as discussed above. The following are all valid, and `signer` + /// is parsed as both a subcommand and a value in the second case. + /// + /// ```notrust + /// $ program --ui-paths path1 signer + /// $ program --ui-paths path1 --ui-paths signer signer + /// ``` + /// /// # Examples /// /// ```rust @@ -2036,6 +2066,9 @@ impl<'a, 'b> Arg<'a, 'b> { /// assert_eq!(res.unwrap_err().kind, ErrorKind::UnknownArgument); /// ``` /// [option]: ./struct.Arg.html#method.takes_value + /// [options]: ./struct.Arg.html#method.takes_value + /// [subcommands]: ./struct.SubCommand.html + /// [positionals]: ./struct.Arg.html#method.index /// [`Arg::number_of_values(1)`]: ./struct.Arg.html#method.number_of_values /// [`Arg::multiple(true)`]: ./struct.Arg.html#method.multiple pub fn multiple(self, multi: bool) -> Self {