Question

I am learning Groovy CliBuilder and I find it great, except, I don’t know how to recognise wrong arguments. Consider the following example code:

def cli = new CliBuilder()
cli.s args: 1, longOpt: 'sdkdir', 'sdkdir usage info'
cli.h args: 0, longOpt: 'help', 'print usage information'
def opt = cli.parse(args)
if (!opt) {
    //how to be in this case? seems I can never reach here
    println "something went wrong, but I don't know what"
} else if (opt.h) {
    cli.usage()
} else (!opt.s) {
    println "missing required option -s, try with --help for more information"
} else {
    //do something
}

If I call my script with, for instance, -p, which is an invalid option nothing happens. Similarly, if I add arguments after the options they aren’t detected too.

How can I detect and signal the error?

Also, a small inconvenience is that in my example -s is a required parameter, so in theory, I could add required: true, in practice I can’t or it would be required also with -h, but I think testing it with an if is fine, unless there is a better way.

My real problem is about finding unwanted options and arguments. Any help appreciated, thank you.

UPDATE: Thanks @rodion for your input, I guess I will settle with good enough instead of perfect for the sake of simplicity. Here is what I came up with:

#!/usr/bin/groovy
def cli = new CliBuilder(usage: 'cliTest -s sdkdir {projectName}', 
                         header: 'Command line parameter parsing test in Groovy')
cli.s longOpt: 'sdkdir', args: 1, 'sdkdir usage info, REQUIRED'
cli.h longOpt: 'help', 'print usage information'
def opt = cli.parse(args)
def errMsg = "Invalid arguments.\nusage: ${cli.usage}\n" + 
        "Try `cliTest --help' for more information."
if (!opt) {
    //should never happen, since I don't have required parameters in CliBuilder
    println "error processing arguments\n"
} else if (opt.h) {
    cli.usage()
} else if (!opt.s) {
    println errMsg
} else if (opt.arguments().size() != 1) {
    println errMsg
} else {
    println "Creating project ${opt.arguments()[0]}, sdkdir ${opt.s.value}" 
}

This solution is good enough, but not perfect because it doesn’t tell you which parameter is wrong, but just tells you with a concise message or prints usage information. Here are some tests:

$ ./cliTest 
Invalid arguments.
usage: cliTest -s sdkdir {projectName}
Try `cliTest --help' for more information.

$ ./cliTest -a
Invalid arguments.
usage: cliTest -s sdkdir {projectName}
Try `cliTest --help' for more information.

$ ./cliTest -a -s ../sdkdir
Invalid arguments.
usage: cliTest -s sdkdir {projectName}
Try `cliTest --help' for more information.

$ ./cliTest -s ../sdkdir
Invalid arguments.
usage: cliTest -s sdkdir {projectName}
Try `cliTest --help' for more information.

$ ./cliTest -s ../sdkdir projectName
Creating project projectName, sdkdir ../sdkdir

$ ./cliTest -s ../sdkdir projectName wrong
Invalid arguments.
usage: cliTest -s sdkdir {projectName}
Try `cliTest --help' for more information.

$ ./cliTest -s ../sdkdir -a  projectName 
Invalid arguments.
usage: cliTest -s sdkdir {projectName}
Try `cliTest --help' for more information.

$ ./cliTest -s
error: Missing argument for option: s
usage: cliTest -s sdkdir {projectName}
Command line parameter parsing test in Groovy
 -h,--help           print usage information
 -s,--sdkdir <arg>   sdkdir usage info, REQUIRED
error processing arguments

For my purposes, I’m more than satisfied, but if anyone knows a better way, let me know.

Also, I figured out that the !opt case can happen when there is a required: true option and the argument is missing, but from my understanding it can never be used, since otherwise is not possible to have an help option alone.

Answer 1

This seems to be related to this issue. Apparently you can inspect opt after parsing (but if it’s null, then I guess you are left with nothing). Oh, and the issue is apparenly Not A Bug, hmm… wierd.