Add the ability to retrieve the set's program and parameters.

Modify UsageLine to not include the program name (fetch it with set.Program()).oImprove comments.

v2/getopt.go

@@ -223,17 +223,21 @@ var HelpColumn = 20
 
 // PrintUsage prints the usage line and set of options of set S to w.
 func (s *Set) PrintUsage(w io.Writer) {
-	var params string
+	parts := make([]string, 2, 4)
+	parts[0] = "Usage:"
+	parts[1] = s.program
+	if usage := s.UsageLine(); usage != "" {
+		parts = append(parts, usage)
+	}
 	if s.parameters != "" {
-		params = " " + s.parameters
+		parts = append(parts, s.parameters)
 	}
-	fmt.Fprintf(w, "Usage: %s%s\n", s.UsageLine(), params)
+	fmt.Fprintln(w, strings.Join(parts, " "))
 	s.PrintOptions(w)
-
 }
 
-// UsageLine returns the usage line for the set s.  The set's parameters,
-// if any, are not included.
+// UsageLine returns the usage line for the set s.  The set's program name and
+// parameters, if any, are not included.
 func (s *Set) UsageLine() string {
 	sort.Sort(s.options)
 	flags := ""
@@ -286,9 +290,9 @@ func (s *Set) UsageLine() string {
 	}
 	flags = strings.Join(opts, "] [")
 	if flags != "" {
-		flags = " [" + flags + "]"
+		flags = "[" + flags + "]"
 	}
-	return s.program + flags
+	return flags
 }
 
 // PrintOptions prints the list of options in s to w.

v2/options/options.go

@@ -1,10 +1,11 @@
 // Package options is under development and may be moved in the future.
 // 26 July 2018
 //
-// Package options provides a structured interface to the getopt package.  It is
-// particularly helpful for parsing an option set more than once and possibly
-// concurrently.  This package was designed to make option specification simpler
-// and more concise.
+// Package options provides a structured interface for getopt style flag
+// parsing.  It is particularly helpful for parsing an option set more than once
+// and possibly concurrently.  This package was designed to make option
+// specification simpler and more concise.  It is a wrapper around the getopt
+// package github.com/pborman/getopt/v2 package.
 //
 // Option Decorations
 //

v2/options/options_test.go

@@ -26,7 +26,7 @@ var myOptions = theOptions{
 // This is the help we expect from theOptions.  If you change theOptions then
 // you must change this string.  Note that getopt.HelpColumn must be set to 25.
 var theHelp = `
-Usage:  [-v] [-c COUNT] [--lazy value] [-n NUMBER] [--name NAME] [--timeout value] [parameters ...]
+Usage: program [-v] [-c COUNT] [--lazy value] [-n NUMBER] [--name NAME] [--timeout value] [parameters ...]
  -c, --count=COUNT    number of widgets
      --lazy=value     unspecified
  -n NUMBER            set n to NUMBER
@@ -56,6 +56,7 @@ func TestHelp(t *testing.T) {
 		t.Errorf("RegisterNew returned type %T, want %T", dopts, opts)
 	}
 	var buf bytes.Buffer
+	s.SetProgram("program")
 	s.PrintUsage(&buf)
 	if help := buf.String(); help != theHelp {
 		t.Errorf("Got help:\n%s\nWant:\n%s", help, theHelp)

v2/set.go

@@ -144,6 +144,10 @@ func (s *Set) SetParameters(parameters string) {
 	s.parameters = parameters
 }
 
+// Parameters returns the parameters set by SetParameters on s.
+func (s *Set) Parameters() string { return s.parameters }
+
+
 // SetProgram sets the program name to program.  Normally it is determined
 // from the zeroth command line argument (see os.Args).
 func SetProgram(program string) {
@@ -156,6 +160,9 @@ func (s *Set) SetProgram(program string) {
 	s.program = program
 }
 
+// Program returns the program name associated with Set s.
+func (s *Set) Program() string { return s.program }
+
 // SetUsage sets the function used by Parse to display the commands usage
 // on error.  It defaults to calling PrintUsage(os.Stderr).
 func SetUsage(usage func()) {