clap/examples/18_builder_macro.rs

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#[macro_use]
extern crate clap;
// Note, there isn't a need for "use clap::{ ... };" Because the clap_app! macro uses
// $crate:: internally
fn main() {
// Validation example testing that a file exists
let file_exists = |path| {
if std::fs::metadata(path).is_ok() {
Ok(())
} else {
Err(String::from("File doesn't exist"))
}
};
// External module may contain this subcommand. If this exists in another module, a function is
// required to access it. Recommend `fn clap() -> Clap::SubCommand`.
let external_sub_command = clap_app!( @subcommand foo =>
(@arg bar: -b "Bar")
);
let matches = clap_app!(MyApp =>
(@setting SubcommandRequiredElseHelp)
(version: "1.0")
(author: "Alice")
(about: "Does awesome things")
(@arg config: -c --config <conf> #{1, 2} {file_exists} "Sets a custom config file")
(@arg proxyHostname: --("proxy-hostname") +takes_value "Sets the hostname of the proxy to use")
(@arg input: * "Input file")
(@group test =>
(@attributes +required)
(@arg output: "Sets an optional output file")
(@arg debug: -d ... "Turn debugging information on")
)
(subcommand: external_sub_command)
(@subcommand test =>
(about: "does testing things")
(version: "2.5")
(@arg list: -l "Lists test values")
(@arg test_req: -r requires[list] "Tests requirement for listing")
(@arg aaaa: --aaaa +takes_value {
|a| if a.contains("a") {
Ok(())
} else {
Err(String::from("string does not contain at least one a"))
}
} "Test if the argument contains an a")
)
).get_matches();
// You can check the value provided by positional arguments, or option arguments
if let Some(o) = matches.value_of("output") {
println!("Value for output: {}", o);
}
if let Some(c) = matches.value_of("config") {
println!("Value for config: {}", c);
}
// You can see how many times a particular flag or argument occurred
// Note, only flags can have multiple occurrences
match matches.occurrences_of("debug") {
0 => println!("Debug mode is off"),
1 => println!("Debug mode is kind of on"),
2 => println!("Debug mode is on"),
3 | _ => println!("Don't be crazy"),
}
// You can check for the existence of subcommands, and if found use their
// matches just as you would the top level app
if let Some(ref matches) = matches.subcommand_matches("test") {
// "$ myapp test" was run
if matches.is_present("list") {
// "$ myapp test -l" was run
println!("Printing testing lists...");
} else {
println!("Not printing testing lists...");
}
}
// Continued program logic goes here...
}