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/// `ArgGroup`s are a family of related arguments and way for you to say, "Any of these arguments".
/// By placing arguments in a logical group, you can make easier requirement and exclusion rules
/// instead of having to list each individually, or when you want a rule to apply "any but not all"
/// arguments.
///
/// For instance, you can make an entire `ArgGroup` required, this means that one (and *only* one)
/// argument from that group must be present. Using more than one argument from an `ArgGroup` causes
/// a failure (graceful exit).
///
/// You can also do things such as name an `ArgGroup` as a confliction or requirement, meaning any
/// of the arguments that belong to that group will cause a failure if present, or must 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.
extern crate clap;
use clap::{App, Arg, ArgGroup};
fn main() {
// Create application like normal
let matches = App::new("myapp")
// Add the version arguments
.args_from_usage("--set-ver [ver] 'set version manually'
--major 'auto inc major'
--minor 'auto inc minor'
--patch 'auto inc patch'")
// Create a group, make it required, and add the above arguments
.group(ArgGroup::with_name("vers")
.required(true)
.args(&["ver", "major", "minor", "patch"]))
// Arguments can also be added to a group individually, these two arguments
// are part of the "input" group which is not required
.arg(Arg::from_usage("[INPUT_FILE] 'some regular input'")
.group("input"))
.arg(Arg::from_usage("--spec-in [SPEC_IN] 'some special input argument'")
.group("input"))
// Now let's assume we have a -c [config] argument which requires one of
// (but **not** both) the "input" arguments
.arg(Arg::with_name("config")
.short("c")
.takes_value(true)
.requires("input"))
.get_matches();
// Let's assume the old version 1.2.3
let mut major = 1;
let mut minor = 2;
let mut patch = 3;
// See if --set-ver was used to set the version manually
let version = if let Some(ver) = matches.value_of("ver") {
format!("{}", ver)
} else {
// Increment the one requested (in a real program, we'd reset the lower numbers)
let (maj, min, pat) = (matches.is_present("major"),
matches.is_present("minor"),
matches.is_present("patch"));
match (maj, min, pat) {
(true, _, _) => major += 1,
(_, true, _) => minor += 1,
(_, _, true) => patch += 1,
_ => unreachable!(),
};
format!("{}.{}.{}", major, minor, patch)
};
println!("Version: {}", version);
// Check for usage of -c
if matches.is_present("config") {
let input = matches.value_of("INPUT_FILE").unwrap_or(matches.value_of("SPEC_IN").unwrap());
println!("Doing work using input {} and config {}",
input,
matches.value_of("config").unwrap());
}
}
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