added used of cobra arg constraints

examples/democoin/x/cool/client/cli/tx.go

@@ -3,7 +3,6 @@ package cli
 import (
 	"fmt"
 
-	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 
@@ -20,11 +19,8 @@ func QuizTxCmd(cdc *wire.Codec) *cobra.Command {
 	return &cobra.Command{
 		Use:   "cool [answer]",
 		Short: "What's cooler than being cool?",
+		Args:  cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
-			if len(args) != 1 || len(args[0]) == 0 {
-				return errors.New("You must provide an answer")
-			}
-
 			ctx := context.NewCoreContextFromViper().WithDecoder(authcmd.GetAccountDecoder(cdc))
 
 			// get the from address from the name flag
@@ -56,11 +52,8 @@ func SetTrendTxCmd(cdc *wire.Codec) *cobra.Command {
 	return &cobra.Command{
 		Use:   "setcool [answer]",
 		Short: "You're so cool, tell us what is cool!",
+		Args:  cobra.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
-			if len(args) != 1 || len(args[0]) == 0 {
-				return errors.New("You must provide an answer")
-			}
-
 			ctx := context.NewCoreContextFromViper().WithDecoder(authcmd.GetAccountDecoder(cdc))
 
 			// get the from address from the name flag

examples/democoin/x/pow/client/cli/tx.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"strconv"
 
-	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 
 	"github.com/cosmos/cosmos-sdk/client/context"
@@ -19,13 +18,8 @@ func MineCmd(cdc *wire.Codec) *cobra.Command {
 	return &cobra.Command{
 		Use:   "mine [difficulty] [count] [nonce] [solution]",
 		Short: "Mine some coins with proof-of-work!",
+		Args:  cobra.ExactArgs(4),
 		RunE: func(cmd *cobra.Command, args []string) error {
-			if len(args) != 4 {
-				return errors.New("You must provide a difficulty, a count, a solution, and a nonce (in that order)")
-			}
-
-			// get from address and parse arguments
-
 			ctx := context.NewCoreContextFromViper().WithDecoder(authcmd.GetAccountDecoder(cdc))
 
 			from, err := ctx.GetFromAddress()