Feature request: support MatchValid(PositionalArgs) OR MinimumValidNArgs, MaximumValidNArgs, RangeValidArgs

[eine]

For consistency, I think it would be useful to have MinimumValidNArgs(int), MaximumValidNArgs(int) and RangeValidArgs(min, max) added to the list of supported Args formats. The complete list would then be:

• NoArgs
• ArbitraryArgs
• OnlyValidArgs
• MinimumNArgs(int)
• +MinimumValidNArgs(int)
• MaximumNArgs(int)
• +MaximumValidNArgs(int)
• ExactArgs(int)
• ExactValidArgs(int)
• RangeArgs(min, max)
• +RangeValidArgs(min, max)

This is because AFAIK it is not possible ATM to combine e.g. MinimumNArgs(1) with OnlyValidArgs.

---

An alternative solution is to provide a built-in function such as matchAll by @Antolius in #745. For example:

func MatchValid(p cobra.PositionalArgs) cobra.PositionalArgs {
	return func(cmd *cobra.Command, args []string) error {
		if err := cobra.OnlyValidArgs(cmd, args); err != nil {
			return err
		}
		if err := p(cmd, args); err != nil {
			return err
		}
		return nil
	}
}

which would allow the following expressions:

• Args: cobra.MatchValid(cobra.MinimumNArgs(1)), ValidArgs: []string{...}
• Args: cobra.MatchValid(cobra.MaximumNArgs(5)), ValidArgs: []string{...}
• Args: cobra.MatchValid(cobra.RangeArgs(1, 5)), ValidArgs: []string{...}
• Args: cobra.MatchValid(cobra.ArbitraryArgs), ValidArgs: []string{...}
• Args: cobra.MatchValid(cobra.ExactArgs(1)), ValidArgs: []string{...}

Certainly, MatchValid can be used implicitly when ValidArgs is defined, so the user is not required to type it. Therefore, OnlyValidArgs and ExactValidArgs can be deprecated from the public API. The list of formats would be:

• NoArgs
• ArbitraryArgs
• MinimumNArgs(int)
• MaximumNArgs(int)
• ExactArgs(int)
• RangeArgs(min, max)

[github-actions]

This issue is being marked as stale due to a long period of inactivity

[eine]

This is still an issue. It will be closed when #841 (or some other solution) is merged.

[johnSchnake]

Took the stale label away since the PR referenced that would fix this is still active.

[marckhouzam]

The alternative solution proposed in the description of this issue is now available thanks to #896 and the new MatchAll(pargs ...PositionalArgs) function:

cobra/args.go

Lines 111 to 112 in 03c3eb7

	// MatchAll allows combining several PositionalArgs to work in concert.
	func MatchAll(pargs ...PositionalArgs) PositionalArgs {

I'm going to go ahead and close this as fixed.

[umarcor]

IMHO, this issue should be kept open until either:

• MinimumValidNArgs, MaximumValidNArgs, RangeValidArgs are supported;
• or, args_test refactorization after generalizing ValidArgs #841 (deprecate ExactValidArgs and test combinations of args validators #1643) is merged;
• or, ValidArgs is removed from the codebase.

Using MatchAll does not solve the inconsistency in the API, which is increasing the maintenance burden because of the misunderstandings and related questions/requests. We should close this issue with a solution, rather than a workaround.

See #745 (comment).