clap/examples/tutorial_builder/04_03_relations.rs
Ed Page c9eef44213 fix: Make arg!(--flag <value>) optional by default
This was ported over from the usage parser which modeled after docopt.
We just never got around to implementing the rest of the syntax.

However, when considering this as a standalone feature, an
`arg!(--flag <value>)`, outside of other context, should be optional.
This is how the help would display it.

Fixes #4206
2022-09-12 17:10:01 -05:00

78 lines
2.7 KiB
Rust

use std::path::PathBuf;
use clap::{arg, command, value_parser, ArgAction, ArgGroup};
fn main() {
// Create application like normal
let matches = command!() // requires `cargo` feature
// Add the version arguments
.arg(arg!(--"set-ver" <VER> "set version manually"))
.arg(arg!(--major "auto inc major").action(ArgAction::SetTrue))
.arg(arg!(--minor "auto inc minor").action(ArgAction::SetTrue))
.arg(arg!(--patch "auto inc patch").action(ArgAction::SetTrue))
// Create a group, make it required, and add the above arguments
.group(
ArgGroup::new("vers")
.required(true)
.args(["set-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!([INPUT_FILE] "some regular input")
.value_parser(value_parser!(PathBuf))
.group("input"),
)
.arg(
arg!(--"spec-in" <SPEC_IN> "some special input argument")
.value_parser(value_parser!(PathBuf))
.group("input"),
)
// Now let's assume we have a -c [config] argument which requires one of
// (but **not** both) the "input" arguments
.arg(
arg!(config: -c <CONFIG>)
.value_parser(value_parser!(PathBuf))
.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.get_one::<String>("set-ver") {
ver.to_owned()
} else {
// Increment the one requested (in a real program, we'd reset the lower numbers)
let (maj, min, pat) = (
matches.get_flag("major"),
matches.get_flag("minor"),
matches.get_flag("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.contains_id("config") {
let input = matches
.get_one::<PathBuf>("INPUT_FILE")
.unwrap_or_else(|| matches.get_one::<PathBuf>("spec-in").unwrap())
.display();
println!(
"Doing work using input {} and config {}",
input,
matches.get_one::<PathBuf>("config").unwrap().display()
);
}
}