a bit of refactoring; added new custom errors

cmd/enbas/add.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"errors"
 	"flag"
 	"fmt"
 
@@ -24,9 +23,9 @@ func newAddCommand(name, summary string) *addCommand {
 		accountIDs: accountIDs(emptyArr),
 	}
 
-	command.StringVar(&command.toResourceType, "add-to", "", "specify the type of resource to add to")
+	command.StringVar(&command.toResourceType, addToFlag, "", "specify the type of resource to add to")
 	command.StringVar(&command.listID, listIDFlag, "", "the ID of the list to add to")
-	command.Var(&command.accountIDs, "account-id", "the ID of the account to add to the list")
+	command.Var(&command.accountIDs, accountIDFlag, "the ID of the account to add to the list")
 
 	command.Usage = commandUsageFunc(name, summary, command.FlagSet)
 
@@ -61,7 +60,7 @@ func (c *addCommand) addAccountsToList(gtsClient *client.Client) error {
 	}
 
 	if len(c.accountIDs) == 0 {
-		return errors.New("no account IDs has been specified")
+		return noAccountIDsSpecifiedError{}
 	}
 
 	if err := gtsClient.AddAccountsToList(c.listID, []string(c.accountIDs)); err != nil {

cmd/enbas/errors.go

@@ -23,3 +23,17 @@ type invalidTimelineCategoryError struct {
 func (e invalidTimelineCategoryError) Error() string {
 	return "'" + e.category + "' is not a valid timeline category (please choose home, public, tag or list)"
 }
+
+type unknownSubcommandError struct {
+	subcommand string
+}
+
+func (e unknownSubcommandError) Error() string {
+	return "unknown subcommand '" + e.subcommand + "'"
+}
+
+type noAccountIDsSpecifiedError struct{}
+
+func (e noAccountIDsSpecifiedError) Error() string {
+	return "no account IDs specified"
+}

cmd/enbas/main.go

@@ -8,11 +8,14 @@ import (
 
 const (
 	accountFlag           = "account"
+	accountIDFlag         = "account-id"
+	addToFlag             = "add-to"
 	instanceFlag          = "instance"
 	listIDFlag            = "list-id"
 	listTitleFlag         = "list-title"
 	listRepliesPolicyFlag = "list-replies-policy"
 	myAccountFlag         = "my-account"
+	removeFromFlag        = "remove-from"
 	resourceTypeFlag      = "type"
 	statusIDFlag          = "status-id"
 	tagFlag               = "tag"
@@ -107,7 +110,8 @@ func run() error {
 		executor = newRemoveCommand(remove, summaries[remove])
 	default:
 		flag.Usage()
-		return fmt.Errorf("unknown subcommand %q", subcommand)
+
+		return unknownSubcommandError{subcommand}
 	}
 
 	if err := executor.Parse(args); err != nil {

cmd/enbas/remove.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"errors"
 	"flag"
 	"fmt"
 
@@ -24,9 +23,9 @@ func newRemoveCommand(name, summary string) *removeCommand {
 		accountIDs: accountIDs(emptyArr),
 	}
 
-	command.StringVar(&command.fromResourceType, "remove-from", "", "specify the type of resource to remove from")
+	command.StringVar(&command.fromResourceType, removeFromFlag, "", "specify the type of resource to remove from")
 	command.StringVar(&command.listID, listIDFlag, "", "the ID of the list to remove from")
-	command.Var(&command.accountIDs, "account-id", "the ID of the account to remove from the list")
+	command.Var(&command.accountIDs, accountIDFlag, "the ID of the account to remove from the list")
 
 	command.Usage = commandUsageFunc(name, summary, command.FlagSet)
 
@@ -61,7 +60,7 @@ func (c *removeCommand) removeAccountsFromList(gtsClient *client.Client) error {
 	}
 
 	if len(c.accountIDs) == 0 {
-		return errors.New("no account IDs has been specified")
+		return noAccountIDsSpecifiedError{}
 	}
 
 	if err := gtsClient.RemoveAccountsFromList(c.listID, []string(c.accountIDs)); err != nil {