Clap

A basic command-line argument parser with a fluent interface.

• Supports short (-h) and long (--help) option names.
• Handles positional arguments.
• Generates formatted usage text.
• Binds to variables for value retrieval (bool, string and numeric types).

#include <emergent/Clap.hpp>
using namespace emergent;

int main(int argc, char *argv[])
{
    bool help       = false;
    long iterations = 100;
    string mode     = "normal";
    string path     = "";
    
    Clap clap;
    clap['h'].Name("help") .Describe("display this help information")     .Bind(help);
    clap['i']              .Describe("numeric value without a long name") .Bind(iterations);
    clap['m'].Name("mode") .Describe("simple string bind")                .Bind(mode);
    clap[1]  .Name("path") .Describe("first positional argument")         .Bind(path);
    
    // Invoke the parser
    clap.Parse(argc, argv);
    
    if (help)
    {
        // Print usage text to std::cout
        clap.Usage(cout, argv[0]);
        return 0;
    }
    
    // ...
    
    return 0;
}

which will display the following usage text

usage: process-name [options] <path>

  <path>              first positional argument
                       
  -h, --help          display this help information
  -i <value>          numeric value without a long name
  -m, --mode=<value>  simple string bind

If an option is referred to multiple times in a single command-line then only the final one will apply; however if you bind to a std::vector<> then every value for that option type will be stored in order. Additionally you can bind to a function that accepts a string value.

Clap will throw exceptions under the following conditions:

• Unknown option.
• Expected value missing for a non-flag option.
• Incorrect value type (for example, attempting to pass a string to a numeric option).
• An option that has not been bound to a variable will except when used.
• Duplicate short name, long name or position.