A clap-rs inspired command line argument parser design for zig

clap-sample.zig

const print = @import("std").debug.print;

const clap = @import("clap");
const Arg = clap.Arg;
const Subcommand = clap.Subcommand;

const Cli = clap.Parser(struct {
    name: Arg(?[]const u8, .{
        .short = "n",
        .help = "Optional name to operate on",
    }),
    debug: Arg(u8, .{
        .short = "d",
        .help = "Turn debugging information on",
    }),
    command: ?Commands,
}, .{
    .about = "This is a test program",
    .long_about = "This is a test program, to fuzz test zig program",
});

const Commands = union(enum) {
    @"test": Subcommand(struct {
        list: Arg(bool, .{
            .short = "l",
            .help = "lists test values",
        }),
        command: ?TestCommands,
    }, .{
        .help = "does testing things",
    }),
    start: Subcommand(struct {
        config: Arg([]const u8, .{
            .short = "c",
            .parser = config_parser,
            .help = "The config file path",
        }),
    }, .{
        .help = "Start the server",
    }),
};

const TestCommands = union(enum) {
    simple: Subcommand(struct {
        arg1: Arg([]const u8, .{}),
        arg2: Arg(u32, .{ .parser = u32_parser }),
    }, .{
        .help = "Show simple test report",
    }),
    full: Subcommand(struct {
        arg1: Arg([]const u8, .{}),
        arg2: Arg(u32, .{}),
    }, .{
        .help = "Show full test report",
    }),
};

fn config_parser(input: []const u8) ![]const u8 {
    return error.InvalidConfig;
}

fn u32_parser(input: []const u8) !u32 {
    return error.InvalidNumber;
}

pub fn main() !void {
    const cli = Cli.parse();

    print("name: {}, debug: {}\n", .{ cli.name, cli.debug });

    if (cli.command) |commands| {
        switch (commands) {
            .@"test" => |cmd| {
                print("test with list: {}", .{cmd.list});
                if (cmd.command) |sub_cmds| {
                    switch (sub_cmds) {
                        .simple => |sub_cmd| {
                            print("test simple, arg1: {}, arg2: {}\n", .{ sub_cmd.arg1, sub_cmd.arg2 });
                        },
                        .full => |sub_cmd| {
                            print("test full, arg1: {}, arg2: {}\n", .{ sub_cmd.arg1, sub_cmd.arg2 });
                        },
                    }
                }
            },
            .start => |cmd| {
                print("start server, {}\n", .{cmd.config});
            },
        }
    }
}