Use cobra feature to check Args

Using a cobra feature allow a reduction of code.

cmd/new.go

@@ -72,16 +72,13 @@ var newCmd = &cobra.Command{
 	Use:     "new [path]",
 	Short:   "Create new content for a campaign",
 	Example: "paperboy new the-announcement.md",
+	Args:    cobra.ExactArgs(1),
 	RunE: func(cmd *cobra.Command, args []string) error {
 		cfg, err := config.LoadConfig()
 		if err != nil {
 			return err
 		}
 
-		if len(args) < 1 {
-			return newUserError("please provide a path")
-		}
-
 		path := cfg.AppFs.ContentPath(args[0])
 		return writeTemplate(cfg.AppFs, path, contentTemplate, map[string]string{
 			"Date":    time.Now().Format(time.RFC3339),
@@ -94,16 +91,13 @@ var newListCmd = &cobra.Command{
 	Use:     "list [path]",
 	Short:   "Create a new recipient list",
 	Example: "paperboy new list in-the-know",
+	Args:    cobra.ExactArgs(1),
 	RunE: func(cmd *cobra.Command, args []string) error {
 		cfg, err := config.LoadConfig()
 		if err != nil {
 			return err
 		}
 
-		if len(args) < 1 {
-			return newUserError("please provide a path")
-		}
-
 		path := cfg.AppFs.ListPath(args[0])
 		return writeTemplate(cfg.AppFs, path, listTemplate, nil, false)
 	},
@@ -112,6 +106,7 @@ var newListCmd = &cobra.Command{
 var newProjectCmd = &cobra.Command{
 	Use:   "project [path]",
 	Short: "Create new project directory",
+	Args:  cobra.RangeArgs(0, 1),
 	RunE: func(cmd *cobra.Command, args []string) error {
 		path := "."
 		if len(args) > 0 {

cmd/preview.go

@@ -23,16 +23,13 @@ const (
 var previewCmd = &cobra.Command{
 	Use:   "preview [content] [list]",
 	Short: "Preview campaign in browser",
+	Args:  cobra.ExactArgs(2),
 	RunE: func(cmd *cobra.Command, args []string) error {
 		cfg, err := config.LoadConfig()
 		if err != nil {
 			return err
 		}
 
-		if len(args) != 2 {
-			return newUserError("Invalid arguments")
-		}
-
 		// Start server, notifies channel when listening
 		return startAPIServer(cfg, func(mux *http.ServeMux, serverReady chan bool) error {
 

cmd/send.go

@@ -15,6 +15,7 @@ var sendCmd = &cobra.Command{
 	Use:     "send [content] [list]",
 	Short:   "Send campaign to recipients",
 	Example: "paperboy send the-announcement in-the-know",
+	Args:    cobra.ExactArgs(2),
 	// Uncomment the following line if your bare application
 	// has an action associated with it:
 	RunE: func(cmd *cobra.Command, args []string) error {
@@ -23,10 +24,6 @@ var sendCmd = &cobra.Command{
 			return err
 		}
 
-		if len(args) != 2 {
-			return newUserError("Invalid arguments")
-		}
-
 		ctx := withSignalTrap(context.Background())
 		return mail.LoadAndSendCampaign(ctx, cfg, args[0], args[1])
 	},