Swift: Announcing ArgumentParser

Re:Swift: Announcing ArgumentParser by akvadrako on Saturday February 29, 2020 @04:53AM (#22449864)

I can't stand argparse. It's like they tried their hardest to force you to be imperative and prevent composability. For example, instead of being able to define a parser for a subcommand and build a top-lever parser from that, you need to do this:

    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers()
    a = subparsers.add_parser('a')
    a.add_argument('bar')

A better API would look more like this:

    Parser(Subparsers({
       'a': Parser(Arg('bar')),
    }))

On top of that it has a number of bugs in edge cases they refuse to document or fix. For example, you can't have a subcommand that always collects all the remaining arguments as-is. That's a pretty basic use-case when you want to pass those arguments to another program.

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Re:Swift: Announcing ArgumentParser by paulddraper on Saturday February 29, 2020 @05:43AM (#22449995)

Python is indeed an imperative language, along with the others I listed. (Your proposal would indeed be at home in a functional language like LISP.)

But I reject the idea that imperative is bad. You can compose imperative programming fine.

    def my_parser(parser):
        parser.add_argument('bar')

    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers()
    my_parser(subparsers.add_parser('a'))
    my_parser(subparsers.add_parser('a2'))

> you can't have a subcommand that always collects all the remaining arguments as-is.

    parser = argparse.ArgumentParser()
    subparsers = parser.add_subparsers()
    a = subparsers.add_parser('a')
    a.add_argument('args', nargs='*')

That works just fine.

    ./example a arg1 arg2 arg3

    ./example a -- arg1 --look-ma-hyphens-arg2 arg3

If you're complaining about the double hyphen syntax....that's a universal convention for UNIX-ish CLI positional arguments. Otherwise things get really murky.

    ./example a --help

Did I want help on the `a` subcommand, or did I want to pass `--help` to the `a` subcommand? The `--` syntax lets you distinguish.

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Re:Swift: Announcing ArgumentParser by nicoburns on Saturday February 29, 2020 @08:15AM (#22450370)

> Python is indeed an imperative language, along with the others I listed.

JavaScript has functional origins, and in practice quite a bit of JavaScript is written in a functional-lite style. As a JS developer, I find it quite infuriating that Python doesn't support these patterns, as they make code a lot more readable, and it seems to be a matter of principle rather than a technical limitation.

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Re:Swift: Announcing ArgumentParser by hgoury on Monday March 02, 2020 @05:45AM (#22463284)

You should check out click : https://click.palletsprojects.com/en/7.x/

It is very powerful, uses special files stdin/stdout when file argument is "-", supports groups, subcommands...

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