this post was submitted on 28 Jan 2024
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32
In CLI design, how to ask the user for a nested structured input? (lemy.lol)
submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/[email protected]
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Background

I am designing a CLI for a container build tool I am making. It uses Gentoo's Portage behind the scenes

Question

I want to give the user the ability to specify a custom package repository. The repository must have a name, URI and sync type.

custom_repo: {
    uri: 'https://...',
    name: 'custom',
    sync_type: 'git',
}

How do I have the user represent this in the CLI? keep in mind, this is not the main input and is optional.

One way is to make this only provide-able via a config file using JSON or another structured data representation. But I want to see if theres a good way to do it in the CLI

What I am thinking of: command --custom-repo uri='https://...',name=custom,sync_type=git --custom-repo ... [main input]

Is this the best way of doing this?

all 25 comments
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[–] [email protected] 17 points 1 year ago (3 children)

Just pass in the name of a json file as a CLI input (or default the name and act on it if present or use it if indicated [e.g. /U == use json.config]).

[–] [email protected] 7 points 1 year ago

Yea, as a user I'd second the use of a configuration file - that approach tends to be much more convenient to use... especially since most users won't often change these values.

[–] [email protected] 7 points 1 year ago (1 children)

I will definitely make that an option, but I would still want it to be invokable via CLI only if the user chooses. It makes scripting easier sometimes.

[–] [email protected] 5 points 1 year ago

How about a command-line flag to name an input file, but also process input as JSON, so someone can pipe it to your command or hand-write it if they're crazy?

[–] [email protected] 2 points 1 year ago

perhaps also useful in this case to document the shortcut of

<(echo ‘{…}’)

since not many people know about it, and it makes your tool work with things specified entirely on the command line rather than temp files

alternatively —config-file and —config-json or similar

making and cleaning up temp files when writing scripts is just such a massive PITA

[–] [email protected] 12 points 1 year ago

If the json payload is small with finite keys you can support separate args for those keys. If you really need arbitrary json what you have described is fairly reasonable as a shorthand, similar to AWS CLI shorthand.

Honestly passing optional/advanced args as json via CLI isn't usually too bad since you can quote it with single quotes.

[–] [email protected] 9 points 1 year ago (2 children)

Can't this all be deduced from the URI?

https://github.com/org/project.git

The .git suffix indicates git, the project name is the stem (project).

[–] [email protected] 8 points 1 year ago* (last edited 1 year ago)

Nix does something like this with the protocol specifier: e.g. git+https://...

I'm not sure what name means here exactly, but it might make sense to treat that separately, like git remotes:

tool add [name] git+https://foo

[–] [email protected] 2 points 1 year ago (1 children)

That is assuming it's hosted on github.

[–] [email protected] 0 points 1 year ago (1 children)

That is an example URI.

[–] [email protected] 3 points 1 year ago* (last edited 1 year ago) (1 children)

Ok, then I don't understand at all. What happens if I host my git project on https://myawesomeproject.dev/? How can the application infer anything by this URL?

[–] [email protected] 0 points 1 year ago (2 children)

Then replace "github.com" with "myawesomeproject.dev". There's more to the URI than just the hostname.

[–] [email protected] 3 points 1 year ago (1 children)

But you can't assume that it follows the github format of https://<domain>/<user>/<project>.git. In my example, I meant that you would just use that url to clone it:

git clone https://myawesomeproject.dev

One real-world example of this is ziglings.org (though it's technically just a redirect).

[–] [email protected] -1 points 1 year ago (1 children)

That's not a GitHub format; it's a git format.

[–] [email protected] 3 points 1 year ago

No, it isn't. Git doesn't care what the url is, as long as it uses a supported transport protocol.

[–] [email protected] 6 points 1 year ago

For something like that i'd take a parameter like this (repeated as necessary):

--custom-repo=<name>=<synctype>+<url>

for example:

--custom-repo=custom=git+https://github.com/matcha/custom

[–] [email protected] 2 points 1 year ago

You could read json from standard input. Ex:

echo &lt;&lt; EOF | command --read-stdin
    Some JSON
EOF
[–] [email protected] 2 points 1 year ago

What language? This would be simple with Python's argparse or Go's pflag.

[–] [email protected] 2 points 1 year ago

command --git-url https://... --alias myalias --svn-url http://... --alias mysvnalias

You may process it as a stack.

When reading within the program from stdin I recommend a state machine.

[–] [email protected] 2 points 1 year ago

I'm having the same problem. this kind of nested argument is quite annoying to program in e.g. argp. i am even thinking of using a minimal forth like parser to do this.

[–] [email protected] 1 points 1 year ago (1 children)

Ask the user to customize a preset.json?

[–] [email protected] 2 points 1 year ago

That is certainly one solution and I plan to make that an option. But I'd still like to make the program invokable without having to write a file.

[–] [email protected] 0 points 1 year ago (1 children)

command --custom-repo-uri https://foo.com --custom-repo-name repo_name --custom-repo-sync-type git

[–] [email protected] 2 points 1 year ago

There could be multiple custom repos, so it would be difficult to know which uri goes with which repo name, and so on.