Error: "value" not unique - when matching name and alias for same object

[StaffanArvidsson]

Found that having e.g. the name and aliases begin with the same letters result in strange bahaviour when it comes to allowing abbreviated commands. Say I have the following snippet out of the generated usage text;

COMMANDS
  chemical-files, chem-formats ...

and then running with .. chem will fail with the following stack trace (running CommandLine.execute(String)):

picocli.CommandLine$ParameterException: Error: 'chem' is not unique: it matches 'chemical-files', 'chem-formats'
	at picocli.CommandLine$AbbreviationMatcher.match(CommandLine.java:18426)
	at picocli.CommandLine$Interpreter.processArguments(CommandLine.java:13306)
	at picocli.CommandLine$Interpreter.parse(CommandLine.java:13122)
	at picocli.CommandLine$Interpreter.processSubcommand(CommandLine.java:13395)
	at picocli.CommandLine$Interpreter.processArguments(CommandLine.java:13310)

I guess that's because the code builds up a Map<String,Object> of each name/alias and the AbbreviationMatcher doesn't check that they reference the same objects?

[remkop]

Hi @StaffanArvidsson, thanks for raising this!

Unfortunately I cannot reproduce the issue. Please take a look at the test I added.
In my test, both the execute method and the parseResult method behave as I expect them to behave:

• The execute method does not throw an exception, and does not show a stack trace, but shows a user-friendly error message.
• The parseArgs method does throw an exception, but the stacktrace looks very different from the one in the question. This is the stack trace I am seeing:

picocli.CommandLine$UnmatchedArgumentException: Unmatched argument at index 0: 'chem'

	at picocli.CommandLine$Interpreter.validateConstraints(CommandLine.java:13202)
	at picocli.CommandLine$Interpreter.parse(CommandLine.java:13154)
	at picocli.CommandLine$Interpreter.parse(CommandLine.java:13100)
	at picocli.CommandLine$Interpreter.parse(CommandLine.java:13001)
	at picocli.CommandLine.parseArgs(CommandLine.java:1478)
	at picocli.Issue1537Ambiguous.testParseArgs(Issue1537Ambiguous.java:38)

Can you provide a way to reproduce the issue?

[NewbieOrange]

@StaffanArvidsson probably means the following:

int exitCode = new CommandLine(new MyCommand()).setAbbreviatedSubcommandsAllowed(true).execute("chem");

Which does give a user-friendly error message, but the result may be confusing to end-users:

Error: 'chem' is not unique: it matches 'chemical-files', 'chem-formats'
Usage: <main class> [COMMAND]
Commands:
  chemical-files, chem-formats

I can create a pull request to get this fixed if needed.

[StaffanArvidsson]

Yes @NewbieOrange is correct, I had set setAbbreviatedSubcommandsAllowed(boolean), perhaps I should have stated that explicitly more than the stack trace and given that 'chem' doesn't match any of the names. So I guess it could be thought of like a feature request, but my assumption would be that given that the matches produced by the AbbreviationMatcher are unique for a single command object - that object should be selected and executed. Is there a situation where this is undesireble?

[remkop]

Thank you for your patience. I was finally able to reproduce the issue. 😅

Yes, I agree that it would be nice improvement to not fail when there are multiple matching candidate names which all reference the same command object (so there is no real ambiguity).

@NewbieOrange if you can work on this, that would be great! 🙏