Support subcommands based on program name

[adworacz]

Use case:
In some circumstances, it's extremely useful to change a program's behavior based on the name it is invoked with.

A common example is something like BusyBox, where it is in fact a single binary that is symlinked to, often multiple times (like ls -> busybox, cp -> busybox, etc) . It then changes its behavior based off the name of the program (the symlink).

It would be useful for optique to support something like this, even if it's just exposing the name of the program. Something more advanced would be something like a command, where a specific set of program names are supported, and they take their own subset of options, and possibly their own help text.

[dahlia]

Thanks for the suggestion! This is an interesting use case.

I believe this is already achievable with the current API. The run() function accepts both programName and args as overridable options, so you can read the invoked name yourself and dispatch accordingly.

For example, you can inject the basename as a synthetic subcommand:

import path from "node:path";
import { run } from "@optique/run";
import { command, or } from "@optique/core/parser";

const invokedName = path.basename(process.argv[1]);

const parser = or(
  command("cat", catParser),
  command("ls", lsParser),
  command("grep", grepParser),
);

await run(parser, {
  programName: invokedName,
  args: [invokedName, ...process.argv.slice(2)],
});

Since command() does exact string matching on the first token in the args array, prepending the basename makes it work as a subcommand selector. The programName override also ensures help text displays the symlink name (e.g., Usage: cat [OPTIONS]).

Alternatively, you can simply select a parser based on the program name without using command() at all:

const parsers: Record<string, Parser<"sync", unknown, unknown>> = {
  cat: catParser,
  ls: lsParser,
};

await run(parsers[invokedName] ?? defaultParser, {
  programName: invokedName,
});

Do you think this covers your use case, or is there something more you'd need from the library?

[adworacz]

Ahh that is an interesting solution! I'll be sure to give this a shot and report back if I run into any issues.

Thanks for your work and help on this issue!