Mechiru.Command

Mechiru.Command is the simplest command line argument parser.
🚧 This library is implemented for container applications and has some limitations. 🚧

record Opt(
    [Option] string Foo,
    [Option] bool Bar
);

Console.WriteLine(ArgumentParser.ParseDefault<Opt>());

$ dotnet run --foo hello --bar
Opt { Foo = hello, Bar = True }

TargetFrameworks

.NET 5+

Notice

You can also use the standard argument parser instead of relying on a third party library.
Check this documentation for details.

Features:

• Support environment variables commandlineparser/commandline#677
• Default value from function through interface
• Record class friendly

Examples

Required arguments

record Opt([Option(Required = true)] string Foo);
Console.WriteLine(ArgumentParser.ParseDefault<Opt>());

$ dotnet run
Unhandled exception. System.ArgumentException: required option not specified: `foo`
   at Mechiru.Command.ArgumentParser.ParseInner(IEnumerable`1 args, ArgSpec[] specs)
   at Mechiru.Command.ArgumentParser.Parse[T](IEnumerable`1 args)
   at Mechiru.Command.ArgumentParser.ParseDefault[T]()
   at test.Program.Main(String[] args) in /tmp/test/Program.cs:line 12

Environment variables

record Opt([Option(Env = true)] string Foo);
Console.WriteLine(ArgumentParser.ParseDefault<Opt>());

$ FOO=fuga dotnet run
Opt { Foo = fuga }

You can also override the name of the environment variable:

record Opt([Option(Env = "MY_FOO")] string Foo);
Console.WriteLine(ArgumentParser.ParseDefault<Opt>());

$ MY_FOO=my-fuga dotnet run
Opt { Foo = my-fuga }

Default values

record Opt([Option(Default = "hoge")] string Foo);
Console.WriteLine(ArgumentParser.ParseDefault<Opt>());

$ dotnet run
Opt { Foo = hoge }

You can also set default value from object:

record Opt([Option(Default = 20)] int Age);
Console.WriteLine(ArgumentParser.ParseDefault<Opt>());

$ dotnet run
Opt { Age = 20 }

You can also set default value from function through interface:

record Opt([Option(Default = typeof(MyDefaultValue))] string Foo);

class MyDefaultValue : IDefault
{
    public object Default() => "value from function";
} 

Console.WriteLine(ArgumentParser.ParseDefault<Opt>());

$ dotnet run
Opt { Foo = value from function }

Custom parsing

record Opt([Option(Parser = typeof(JsonArrayParser))] string[] Values);

class JsonArrayParser : IParser
{
    public object Parse(string s) => JsonSerializer.Deserialize<string[]>(s)!;
}

var opt = ArgumentParser.ParseDefault<Opt>();
Console.WriteLine(string.Join(',', opt.Values));

$ dotnet run --values '["foo", "fuga", "hoge"]'
foo,fuga,hoge

Other examples can be found here.

Lisence

This library is under the MIT License.