docopt VS complgen

Symfony Console closely follows the well-established docopt conventions. Docopt, based on longstanding conventions from help messages and man pages, ensures a consistent and intuitive interface for describing a program's interface. Symfony Console's adherence to docopt conventions guarantees that your command line tools maintain a standardized and predictable user experience, simplifying development and user interaction.

You probably already know, but just in case you don't, you might read about http://docopt.org/ It seems to me a lot of your usage ideas could be refinements of / tooling around docopt-style interfaces.

http://docopt.org/

Not quite what you asked for, but close: type example invocations to generate the CLI, and just pull the arguments from a dictionary at runtime.

I've been using docopt to handle CLI arguments for years now.

http://docopt.org/

If you aren't averse to using a third party package, on my personal projects I always found https://github.com/docopt/docopt to be nice.

You can kill 2 birds with one stone by documenting your scripts while also providing the argument structure / parsing.

As for the implementation differences, complgen uses a trivial DSL that’s everybody is already familiar with more or less because it’s a slightly more rigorous version of what tools usually spit out when you do command --help (projects like docopt even use that for command line arguments parsing). Those happen to be regular languages and therefore can be represented as a Deterministic Finite Automata. complgen compiles the grammars to DFAs, minimizes the DFA and spits out shell-specific shell completions scripts that simply walk the DFA to match and complete the current input.

The current completion system has a list of rules of which completions to use at which time. It's purposely simple to make it as flexible as possible. The current things I'm planning is a derive macro like what clap has to generate these rules. I'm also considering introducing a plugin that let's you write rules in the format of docopt

For anyone unfamiliar, docopt is an established standard for specifying arguments in a script’s doc string. I use it for Python and it’s lovely. You’re going to write a docstring with examples anyway, why not make them functional?

http://docopt.org/

I like http://docopt.org/ a lot. You seem like someone who might have opinions on that.

The advantage complgen has over clap_complete (currently) is that it can generate completions based on an external command output. For example for cargo, you can have this (incomplete yet) grammar that not only completes +toolchains in cargo but also suggest test names in cargo test .