Stop writing CLI validation. Parse it right the first time

Is there no getopt implementation for Typescript? The input this library tries to handle better looks to me like bad design.

"options that depend on options" should not be a thing. Every option should be optional. Even if you have working code that can handle some complex situation, this doesn't make the situation any less unintuitive for the users.

If you need more complex relationships, consider using arguments as well. Top level, or under an option. Yes, they are not named, but since they are mandatory anyway, you are likely to remember their meaning (spaced repetition and all that). They can still be optional (if they come last). Sometimes an argument may need to have multiple parts, like user@host:port You can still parse it instead of validating, if you want.

> mutually exclusive --json, --xml, --yaml.

Use something like -t TYPE instead, where TYPE can be one of json, xml, or yaml. (Make illegal states unrepresentable.)

> debug: optional(option("--debug")),

Again, I believe it's called "option" because it's meant to be optional already.

  optional(optional(option("--common-sense")))

EOR

> options that depend on options

What would you do for "top level option, which can be modified in two other ways"?

  (--option | --option-with-flag1 | --option-with-flag2 | --option-with-flag1-and-flag2)

would solve invalid representation, but is unwieldy.

Something that results in the usage string

  [--option [--flag1 --flag2]]

doesn't seem so bad at that point.

I think I've seen it done like that

  --option flag1,flag2

(Maybe with another separator, as long as it doesn't need to be escaped.)

Another possibility is to make the main option an argument, like the subcommands in git, systemctl, and others:

  command option --flag1 --flag2

This depends on the specifics, though.