pargs

command line argument parser

pargs - command line argument parser

the design goal of pargs is to simply return parsed arguments to a caller in a defined format for ease of lookup.

pargs works with three common types of arguments: commands, flags and options.

Using pargs

using pargs is very simple: define all three types of arguments that your program needs and pass them as individual Vec<String> to pargs::parse(). parse() will return a Matches struct of the parsed arguments keyed by category so that your application can easily interpret them.

The return values of successfully parsed arguments are as follows:

• command_args: Vec<String>
• flag_args: Vec<String>
• option_args: HashMap

Definitions

• command_args are defined as single arguments that do not have an assigned value
• command_args args should be entered without a dash
• flag_args are intended to be boolean values
• flag_args should not be assigned a value - if they exist, they are interpreted as true
• option_args should be assigned a value
• option_args should be denoted with a - character
• option_args can be assigned a value via = or space between arg and value

Example

The following example shows a simple program that defines all three types of arguments (commands, flag and option). Pargs is passed a Vec<String> from env::args() at which point it parses the arguments and returns them to the program in a simple data structure.

use std::env;
use pargs::Pargs;

let actual_args: Vec<String> = env::args().collect();
let command_args = vec![String::from("cool_command")];
let flag_args = vec![String::from("-h")];
let option_args = vec![String::from("-j"), String::from("-i")];

let parsed_args = Pargs::parse(actual_args, command_args, flag_args, option_args);

match parsed_args {
    Ok(parsed_args) => println!("{:?}", parsed_args),
    Err(parsed_args) => println!("{}", parsed_args),
}

If we run this program with cargo run cool_command -h -j=test123 -i=test456, the output will be Matches { command_args: ["cool_command"], flag_args: ["-h"], option_args: {"-i": "test456", "-j": "test123"} }.

From here, we can lookup the values and utilize them in our program.