Flags don't parse after encountering positional parameter

[tlhunter]

Based on what I've read in the documentation I would expect the following to work, but I might have misconfigured something. Essentially I would like to support syntax like what git exposes, ala git status --short command.

Here's some sample code:

	connection := ""
	migrations := ""

	getopt.FlagLong(&connection, "connection", 'c', "SQL connection string")
	getopt.FlagLong(&migrations, "migrations", 'm', "Migrations directory")

	getopt.Parse()

	config := MigConfig{
		Connection: connection,
		Migrations: migrations,
	}

	args := getopt.Args()

	fmt.Println("CONFIG")
	fmt.Println(config)
	fmt.Println("ARGS")
	fmt.Println(args)

	return config, nil

Next, I'm invoking the program in two ways:

$ app status --connection="foo"    
CONFIG
{ }
ARGS
[status --connection=foo]

$ app --connection="foo" status
CONFIG
{foo }
ARGS
[status]

The second invocation works as expected, pulling the flag data out and providing the remaining non-flag arguments via .Args(). However the first invocation, in the style of the git command, wasn't able to parse the flags. Have I configured this wrong or is this expected behavior?

[rkennedy]

There's nothing misconfigured. That's just how this library has been written to work. There's precedent for it; it's how the corresponding GNU function works when the POSIXLY_CORRECT environment variable is set.

It can be useful when the argument list allows subcommands. Arguments to the "main" program aren't necessarily valid for the subcommand. You mention git as inspiration for your use case. The "main" git command accepts -c to specify config options that apply for the current command. But git commit interprets -c to specify a commit ID to populate the commit message from. If we were implementing git using this library, we'd want parsing to stop when it reached the first non-option so we could do subcommand-specific parsing.

I wonder how much effort it would take to make this library support both the POSIX and default GNU behaviors.

[pborman]

@rkennedy is correct, this is now traditional argument processing has been done on UNIX. Try running rm foo -f and it should complain with:

rm: foo: No such file or directory
rm: -f: No such file or directory

I originally wrote this package because you cannot write a compatible ssh program (one that accepts the same arguments) using the Go flags package. AFAIK the Go flags package was actually based on Google's internal C++ flag processing. It is a shame it leaked out into the world.