D Argument Parser 
Better command line argument parsing using D's powerful compile-time code generation facilities.
Note: This is a stable library, but it is no longer maintained. If you'd like to help out with maintanence please make an issue letting me know!
Example
import std.stdio;
import darg;
struct Options
{
@Option("help", "h")
@Help("Prints this help.")
OptionFlag help;
@Option("threads", "t")
@Help("Number of threads to use.")
size_t threads;
@Argument("file", Multiplicity.zeroOrMore)
@Help("Input files")
string[] files;
}
// Generate the usage and help string at compile time.
immutable usage = usageString!Options("example");
immutable help = helpString!Options;
int main(string[] args)
{
Options options;
try
{
options = parseArgs!Options(args[1 .. $]);
}
catch (ArgParseError e)
{
writeln(e.msg);
writeln(usage);
return 1;
}
catch (ArgParseHelp e)
{
// Help was requested
writeln(usage);
write(help);
return 0;
}
foreach (f; options.files)
{
// Use files
}
return 0;
}$ ./example --help
Usage: example [--help] [--threads=<ulong>] [file...]
Positional arguments:
file Input files
Optional arguments:
--help, -h Prints this help.
--threads, -t <ulong>
Number of threads to use.
$ ./example --foobar
Unknown option '--foobar'
Usage: program [--help] [--threads=<ulong>] [file...]