Available on crate feature
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Example: git-like CLI (Builder API)
use std::ffi::OsString;
use std::path::PathBuf;
use clap::{arg, Command};
fn cli() -> Command<'static> {
Command::new("git")
.about("A fictional versioning CLI")
.subcommand_required(true)
.arg_required_else_help(true)
.allow_external_subcommands(true)
.allow_invalid_utf8_for_external_subcommands(true)
.subcommand(
Command::new("clone")
.about("Clones repos")
.arg(arg!(<REMOTE> "The remote to clone"))
.arg_required_else_help(true),
)
.subcommand(
Command::new("push")
.about("pushes things")
.arg(arg!(<REMOTE> "The remote to target"))
.arg_required_else_help(true),
)
.subcommand(
Command::new("add")
.about("adds things")
.arg_required_else_help(true)
.arg(arg!(<PATH> ... "Stuff to add").value_parser(clap::value_parser!(PathBuf))),
)
.subcommand(
Command::new("stash")
.args_conflicts_with_subcommands(true)
.args(push_args())
.subcommand(Command::new("push").args(push_args()))
.subcommand(Command::new("pop").arg(arg!([STASH])))
.subcommand(Command::new("apply").arg(arg!([STASH]))),
)
}
fn push_args() -> Vec<clap::Arg<'static>> {
vec![arg!(-m --message <MESSAGE>).required(false)]
}
fn main() {
let matches = cli().get_matches();
match matches.subcommand() {
Some(("clone", sub_matches)) => {
println!(
"Cloning {}",
sub_matches.get_one::<String>("REMOTE").expect("required")
);
}
Some(("push", sub_matches)) => {
println!(
"Pushing to {}",
sub_matches.get_one::<String>("REMOTE").expect("required")
);
}
Some(("add", sub_matches)) => {
let paths = sub_matches
.get_many::<PathBuf>("PATH")
.into_iter()
.flatten()
.collect::<Vec<_>>();
println!("Adding {:?}", paths);
}
Some(("stash", sub_matches)) => {
let stash_command = sub_matches.subcommand().unwrap_or(("push", sub_matches));
match stash_command {
("apply", sub_matches) => {
let stash = sub_matches.get_one::<String>("STASH");
println!("Applying {:?}", stash);
}
("pop", sub_matches) => {
let stash = sub_matches.get_one::<String>("STASH");
println!("Popping {:?}", stash);
}
("push", sub_matches) => {
let message = sub_matches.get_one::<String>("message");
println!("Pushing {:?}", message);
}
(name, _) => {
unreachable!("Unsupported subcommand `{}`", name)
}
}
}
Some((ext, sub_matches)) => {
let args = sub_matches
.get_many::<OsString>("")
.into_iter()
.flatten()
.collect::<Vec<_>>();
println!("Calling out to {:?} with {:?}", ext, args);
}
_ => unreachable!(), // If all subcommands are defined above, anything else is unreachabe!()
}
// Continued program logic goes here...
}
Git is an example of several common subcommand patterns.
Help:
$ git
? failed
git
A fictional versioning CLI
USAGE:
git[EXE] <SUBCOMMAND>
OPTIONS:
-h, --help Print help information
SUBCOMMANDS:
add adds things
clone Clones repos
help Print this message or the help of the given subcommand(s)
push pushes things
stash
$ git help
git
A fictional versioning CLI
USAGE:
git[EXE] <SUBCOMMAND>
OPTIONS:
-h, --help Print help information
SUBCOMMANDS:
add adds things
clone Clones repos
help Print this message or the help of the given subcommand(s)
push pushes things
stash
$ git help add
git[EXE]-add
adds things
USAGE:
git[EXE] add <PATH>...
ARGS:
<PATH>... Stuff to add
OPTIONS:
-h, --help Print help information
A basic argument:
$ git add
? failed
git[EXE]-add
adds things
USAGE:
git[EXE] add <PATH>...
ARGS:
<PATH>... Stuff to add
OPTIONS:
-h, --help Print help information
$ git add Cargo.toml Cargo.lock
Adding ["Cargo.toml", "Cargo.lock"]
Default subcommand:
$ git stash -h
git[EXE]-stash
USAGE:
git[EXE] stash [OPTIONS]
git[EXE] stash <SUBCOMMAND>
OPTIONS:
-h, --help Print help information
-m, --message <MESSAGE>
SUBCOMMANDS:
apply
help Print this message or the help of the given subcommand(s)
pop
push
$ git stash push -h
git[EXE]-stash-push
USAGE:
git[EXE] stash push [OPTIONS]
OPTIONS:
-h, --help Print help information
-m, --message <MESSAGE>
$ git stash pop -h
git[EXE]-stash-pop
USAGE:
git[EXE] stash pop [STASH]
ARGS:
<STASH>
OPTIONS:
-h, --help Print help information
$ git stash -m "Prototype"
Pushing Some("Prototype")
$ git stash pop
Popping None
$ git stash push -m "Prototype"
Pushing Some("Prototype")
$ git stash pop
Popping None
External subcommands:
$ git custom-tool arg1 --foo bar
Calling out to "custom-tool" with ["arg1", "--foo", "bar"]