Crate gumdrop [−] [src]
Option parser with custom derive support
Example
extern crate gumdrop; #[macro_use] extern crate gumdrop_derive; use std::env::args; use gumdrop::Options; // Defines options that can be parsed from the command line. // // `derive(Options)` will generate an implementation of the trait `Options`. // An implementation of `Default` (derived or otherwise) is required for the // generated implementation. // // (`Debug` is only derived here for demonstration purposes.) #[derive(Debug, Default, Options)] struct MyOptions { // Contains "free" arguments -- those that are not options. // If no `free` field is declared, free arguments will result in an error. #[options(free)] free: Vec<String>, // Boolean options are treated as flags, taking no additional values. // The optional `help` attribute is displayed in `usage` text. #[options(help = "print help message")] help: bool, // Non-boolean fields will take a value from the command line. // Wrapping the type in an `Option` is not necessary, but provides clarity. #[options(help = "give a string argument")] string: Option<String>, // A field can be any type that implements `FromStr`. // The optional `meta` attribute is displayed in `usage` text. #[options(help = "give a number as an argument", meta = "N")] number: Option<i32>, // A `Vec` field will accumulate all values received from the command line. #[options(help = "give a list of string items")] item: Vec<String>, // The `count` flag will treat the option as a counter. // Each time the option is encountered, the field is incremented. #[options(count, help = "increase a counting value")] count: u32, // Option names are automatically generated from field names, but these // can be overriden. The attributes `short = "?"`, `long = "..."`, // `no_short`, and `no_long` are used to control option names. #[options(no_short, help = "this option has no short form")] long_option_only: bool, } fn main() { let args: Vec<String> = args().collect(); // Remember to skip the first argument. That's the program name. let opts = match MyOptions::parse_args_default(&args[1..]) { Ok(opts) => opts, Err(e) => { println!("{}: {}", args[0], e); return; } }; if opts.help { // Printing usage text for the `--help` option is handled explicitly // by the program. // However, `derive(Options)` does generate information about all // defined options. println!("Usage: {} [OPTIONS] [ARGUMENTS]", args[0]); println!(); println!("{}", MyOptions::usage()); } else { println!("{:#?}", opts); } }
Structs
Error |
Represents an error encountered during argument parsing |
Parser |
Parses options from a series of |
Enums
Opt |
Represents an option parsed from a |
ParsingStyle |
Controls behavior of free arguments in |
Traits
Options |
Implements a set of options parsed from command line arguments. |
Functions
parse_args |
Parses arguments from the command line. |
parse_args_default |
Parses arguments from the command line using the default parsing style. |