Improve argument parsing syntax for commands without options

[anthonydahanne]

Using Spring Shell 4, In the tests, we can find this snippet:

    @Command(name = "hi", description = "Say hi to a given name", group = "greetings",
            help = "A command that greets the user with 'Hi ${name}!' with a configurable suffix. Example usage: hi -s=! John")
    public void sayHi(
            @Argument(index = 0, description = "the name of the person to greet",
                    defaultValue = "world") String name,
            @Option(shortName = 's', longName = "suffix", description = "the suffix of the greeting message",
                    defaultValue = "!") char suffix) {
        System.out.println("Hi " + name + suffix);
    }

the example usage says: hi -s=! John which indeed does:

>hi -s=! John
Parsing input: hi -s=! John
Parsed input: ParsedInput[commandName=hi, subCommands=[], options=[CommandOption[shortName=s, longName=, description=null, required=null, defaultValue=null, value=!]], arguments=[CommandArgument[index=0, value=John]]]
Preparing method arguments for method: sayHi of class: com.herodevs.tools.shell.GithubCommand with context: CommandContext[parsedInput=ParsedInput[commandName=hi, subCommands=[], options=[CommandOption[shortName=s, longName=, description=null, required=null, defaultValue=null, value=!]], arguments=[CommandArgument[index=0, value=John]]], commandRegistry=org.springframework.shell.core.command.CommandRegistry@1b472cad, outputWriter=java.io.PrintWriter@27aa0720, inputReader=org.springframework.shell.jline.JLineInputReader@52b2713a]
Processing argument for parameter: name
Processing option for parameter: suffix
Hi John!

but if I want to only override the @Argument without touching the @Option default value, I use hi John:

>hi John
Parsing input: hi John
Parsed input: ParsedInput[commandName=hi, subCommands=[John], options=[], arguments=[]]
Command hi John not found

where John is no longer interpreted as an argument, but rather as a subcommand.

Differently asked, is there a way to have, like we used to in v3, a way to provide a command with a single argument and no options?
What's the v4 for:

    @ShellMethod("example usage:  sayHi John")
    public void sayHi(String name) {
        System.out.println("Hi " + name);
    }

Thank you!

[czpilar]

According to the documentation here: https://docs.spring.io/spring-shell/reference/commands/syntax.html#_options_and_arguments

you can pass argument without any option like this:

$>mycommand -- arg1

[anthonydahanne]

Hello @czpilar
Thanks for your answer, indeed the doc says:

If your command does not have options, then arguments must be separated using "--" (POSIX style) to avoid ambiguity between arguments and subcommands:

$>mycommand -- arg1 arg2

I think usability is pretty diminished with such a change; it seems to be very error prune from a user experience point of view.

Wrt this issue, please close it if it "works as intended" otherwise, if maintainers think usability should be enhanced, it could be left opened.

thank you!

[fmbenhassine]

@anthonydahanne Yes, it is possible to use an argument without an option, you just need to use the new syntax as mentioned in the docs. Thank you @czpilar for the follow up on this!

Wrt this issue, please close it if it "works as intended" otherwise, if maintainers think usability should be enhanced, it could be left opened.

I think we can improve things here, I just didn't find the best way to distinguish arguments from sub commands. So I will keep this issue open for now.

The good thing in v4 is that the CommandParser is now configurable (in contrast to v3) and has a clear contract. So I believe we can provide a smarter parser than the default one and give users choice (posix vs non-posix style, support for option grouping, etc).