Add better usage and error messages

z/cmd.go

@@ -57,6 +57,7 @@ type Cmd struct {
 	MinArgs int  `json:"-"` // minimum number of args required (including parms)
 	MaxArgs int  `json:"-"` // maximum number of args required (including parms)
 	NumArgs int  `json:"-"` // exact number of args required (including parms)
+	NoArgs  bool `json:"-"` // must not have any args
 	MinParm int  `json:"-"` // minimum number of params required
 	MaxParm int  `json:"-"` // maximum number of params required
 	UseConf bool `json:"-"` // requires Z.Conf be assigned
@@ -316,6 +317,9 @@ func (x *Cmd) Run() {
 	}
 
 	switch {
+	case len(args) > 0 && cmd.NoArgs:
+		ExitError(TooManyArgs{cmd})
+		return
 	case len(args) < cmd.MinArgs:
 		ExitError(NotEnoughArgs{cmd})
 		return
@@ -599,8 +603,15 @@ func (x *Cmd) GetAliases() []string { return x.Aliases }
 // GetSummary fulfills the bonzai.Command interface. Uses Fill.
 func (x *Cmd) GetSummary() string { return x.Fill(x.Summary) }
 
-// GetUsage fulfills the bonzai.Command interface. Uses Fill.
+// GetUsage fulfills the bonzai.Command interface. Uses x.Usage if not
-func (x *Cmd) GetUsage() string { return x.Fill(x.Usage) }
+// empty. Otherwise, calls UsageFunc to get usage, then uses Fill.
+func (x *Cmd) GetUsage() string {
+	usage := x.Usage
+	if usage == "" {
+		usage = UsageFunc(x)
+	}
+	return x.Fill(usage)
+}
 
 // GetVersion fulfills the bonzai.Command interface. Uses Fill.
 func (x *Cmd) GetVersion() string { return x.Fill(x.Version) }

z/errors.go

@@ -7,7 +7,10 @@ type NotEnoughArgs struct {
 }
 
 func (e NotEnoughArgs) Error() string {
-	return fmt.Sprintf("not enough args, %v required", e.Cmd.MinArgs)
+	return fmt.Sprintf(
+		"usage: %v %v (not enough args, %v required)",
+		e.Cmd.Name, e.Cmd.GetUsage(), e.Cmd.MinArgs,
+	)
 }
 
 type TooManyArgs struct {
@@ -15,7 +18,10 @@ type TooManyArgs struct {
 }
 
 func (e TooManyArgs) Error() string {
-	return fmt.Sprintf("too many args, %v maximum", e.Cmd.MaxArgs)
+	return fmt.Sprintf(
+		"usage: %v %v (too many args, %v maximum)",
+		e.Cmd.Name, e.Cmd.GetUsage(), e.Cmd.MaxArgs,
+	)
 }
 
 type WrongNumArgs struct {
@@ -23,7 +29,10 @@ type WrongNumArgs struct {
 }
 
 func (e WrongNumArgs) Error() string {
-	return fmt.Sprintf("wrong number of args, %v required", e.Cmd.NumArgs)
+	return fmt.Sprintf(
+		"usage: %v %v (wrong number of args, %v required)",
+		e.Cmd.Name, e.Cmd.GetUsage(), e.Cmd.NumArgs,
+	)
 }
 
 type MissingConf struct {
@@ -71,7 +80,7 @@ type IncorrectUsage struct {
 }
 
 func (e IncorrectUsage) Error() string {
-	return fmt.Sprintf("usage: %v %v", e.Cmd.Name, UsageFunc(e.Cmd))
+	return fmt.Sprintf("usage: %v %v", e.Cmd.Name, e.Cmd.GetUsage())
 }
 
 type MultiCallCmdNotFound struct {