cli parsing: warn on failed parsing

[bjohas]

It seems that sometimes drive fails silently, e.g. if the command line switches aren't correct, e.g. see here #791.

Could there always be a warning if the execution didn't work? (I.e. just a script level failure, not at API level failure.)

[odeke-em]

Unfortunately, short of writing my own commandline parser this won't be something to easily detect.
Here is a sample program at https://play.golang.org/p/NEgNeUVMcb

package main

import (
	"flag"
	"fmt"
)

func main() {
	var name, season string
var verbose bool

	flag.StringVar(&name, "name", "default-name", "the name to set")
	flag.StringVar(&season, "season", "winter", "the current season")
flag.BoolVar(&verbose, "verbose", false, "the verbosity")
	flag.Parse()

	fmt.Printf("name: %s\nprogram: %s\nverbosity: %v", name, season, verbose)
}

when run:

arguments well provided

$ go run main.go --verbose  --name drive
name: drive
program: winter
verbosity: true

misplaced arguments

$ go run main.go --verbose few ones --name drive
name: default-name
program: winter

as you can see, using stdlib package flag to accomodate the request would require creating a new module entirely