mirror of
https://github.com/clap-rs/clap
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91 lines
4.7 KiB
Rust
91 lines
4.7 KiB
Rust
extern crate clap;
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use clap::{App, Arg};
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fn main() {
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// Args describe a possible valid argument which may be supplied by the user at runtime. There
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// are three different types of arguments (flags, options, and positional) as well as a fourth
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// special type of argument, called s (which will be discussed separately).
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//
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// Args are described in the same manner as Apps using the "builder pattern" with multiple
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// methods describing various settings for the individual arguments. Or by supplying a "usage"
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// string. Both methods have their pros and cons.
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//
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// Arguments can be added to applications in two manners, one at a time with the arg(), and
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// arg() method, or multiple arguments at once via a Vec<Arg> inside the args() method,
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// or a single &str describing multiple Args (one per line) supplied to args_from_usage().
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//
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// There are various options which can be set for a given argument, some apply to any of the
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// three types of arguments, some only apply one or two of the types. *NOTE* if you set
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// incompatible options on a single argument, clap will panic! at runtime. This is by design,
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// so that you know right away an error was made by the developer, not the end user.
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//
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// # Help and Version
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// clap automatically generates a help and version flag for you, unless you specify your
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// own. By default help uses "-h" and "--help", and version uses "-V" and "--version". You can
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// safely override "-V" and "-h" to your own arguments, and "--help" and "--version" will still
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// be automatically generated for you.
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let matches = App::new("MyApp")
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// All application settings go here...
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// A simple "Flag" argument example (i.e. "-d") using the builder pattern
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.arg(Arg::with_name("debug")
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.help("turn on debugging information")
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.short('d'))
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// Two arguments, one "Option" argument (i.e. one that takes a value) such
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// as "-c some", and one positional argument (i.e. "myapp some_file")
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.args(&[
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Arg::with_name("config")
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.help("sets the config file to use")
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.takes_value(true)
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.short('c')
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.long("config"),
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Arg::with_name("input")
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.help("the input file to use")
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.index(1)
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.required(true)
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])
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// *Note* the following two examples are convenience methods, if you wish
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// to still get the full configurability of Arg::with_name() and the readability
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// of arg(), you can instantiate a new Arg with Arg::from() and
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// still be able to set all the additional properties, just like Arg::with_name()
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//
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//
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// One "Flag" using a usage string
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.arg("--license 'display the license file'")
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// Two args, one "Positional", and one "Option" using a usage string
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.arg("[output] 'Supply an output file to use'")
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.arg("-i, --int=[IFACE] 'Set an interface to use'")
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.get_matches();
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// Here are some examples of using the arguments defined above. Keep in mind that this is only
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// an example, and may be somewhat contrived
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//
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// First we check if debugging should be on or not
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println!(
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"Debugging mode is: {}",
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if matches.is_present("debug") {
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"ON"
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} else {
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"OFF"
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}
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);
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// Next we print the config file we're using, if any was defined with either -c <file> or
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// --config <file>
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if let Some(config) = matches.value_of("config") {
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println!("A config file was passed in: {}", config);
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}
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// Let's print the <INPUT> file the user passed in. We can use .unwrap() here becase the arg is
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// required, and parsing would have failed if the user forgot it
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println!("Using input file: {}", matches.value_of("input").unwrap());
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// We could continue checking for and using arguments in this manner, such as "license",
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// "output", and "interface". Keep in mind that "output" and "interface" are optional, so you
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// shouldn't call .unwrap(). Instead, prefer using an 'if let' expression as we did with
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// "config"
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}
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