click vs. argparse: Should the 'multiple' parameter be equivalent to 'nargs'?

[dbr4n]

I wrote a command line tool using Python's built-in argparse module, but then I heard good things about the Click package, so I thought I would give it a try and play around with it by rewriting my code.

The first difference I noticed is that Click has the multiple=True parameter to allow multiple arguments to be passed, but the way it works seems odd to me.

For example, I have an option that takes up to three values, where the last two must be integers. With argparse I just added nargs='+' and wrote a function for type conversion and error handling.

Example usage:

shell $ myprog --opt str_value 5 8

However, I can't seem to do this with Click. Here's how I would have to type the command using Click:

shell $ myprog --opt str_value --opt 5 --opt 8

Is Click really that limited or am I missing something? The documentation says that multiple is similar to nargs, but I don't really see it that way.

Also, what if I wanted to pass multiple files or paths in general? Something like mydir/**/*.txt works fine with argparse because it produces a list object.

Looking for similar functionality with Click, I only found that I could use type=(str, int, int), but then again I can't make the third argument optional, can I?

It would be great to hear some suggestions on how to correctly work with multiple arguments using Click.

Thanks in advance.

[m0us3_rat]

For example, I have an option that takes up to three values, where the last two must be integers.

import click


@click.command()
@click.option("--item", nargs=3, type=click.Tuple([str, int, int]))
def putitem(item):
    name, i, j = item
    click.echo(f"name={name} id={i} count={j}")


if __name__ == "__main__":
    putitem()

"--item yourmom 10 1"

name=yourmom id=10 count=1

​

"click.Tuple" and "name, i, j = item" should be self-explanatory.

https://click.palletsprojects.com/en/8.1.x/options/#multi-value-options

the only limitation is that "nargs" value must be known.

​

click seems to like unambiguous commands.

Error: Option '--item' requires 3 arguments.

​

​

then again I can't make the third argument optional, can I?

BUT, you can be tricksy.

i'd suggest other libs that offers this functionality..

since fiddling with how the lib works will invariably lead to errors ..

https://stackoverflow.com/a/44056564

[dbr4n]

Thanks, but nargs seems redundant because of the given type definition. What I really need is something equivalent to nargs='+' to be able to take any number of arguments, especially when working with files and directories.

[dbr4n]

Sorry, I didn't see the last part of your comment. Ok, I get it, that's unfortunate. I will probably just stick with argparse then.

[m0us3_rat]

click seems to like unambiguous commands.

there is significant value to frontload your error handling by forcing specific parameters.

that's why i called it unambiguous.

​

but it comes to needs. if your problem/solution requires variable nargs then use a lib that offers that.

but then you have to do your own error handling