Some code improvements

* Rewrite if-else chain as a switch.
* Rewrite switch statement with only one case as if.
* Remove always true condition.
* Simplify some functions.

command.go

@@ -717,12 +717,12 @@ func (cmd *StringSliceCmd) readReply(rd *proto.Reader) error {
 func stringSliceParser(rd *proto.Reader, n int64) (interface{}, error) {
 	ss := make([]string, 0, n)
 	for i := int64(0); i < n; i++ {
-		s, err := rd.ReadString()
-		if err == Nil {
+		switch s, err := rd.ReadString(); {
+		case err == Nil:
 			ss = append(ss, "")
-		} else if err != nil {
+		case err != nil:
 			return nil, err
-		} else {
+		default:
 			ss = append(ss, s)
 		}
 	}

redis.go

@@ -201,9 +201,7 @@ func (c *baseClient) defaultProcess(cmd Cmder) error {
 			return err
 		}
 
-		err = cn.WithReader(c.cmdTimeout(cmd), func(rd *proto.Reader) error {
-			return cmd.readReply(rd)
-		})
+		err = cn.WithReader(c.cmdTimeout(cmd), cmd.readReply)
 		c.releaseConn(cn, err)
 		if err != nil && internal.IsRetryableError(err, cmd.readTimeout() == nil) {
 			continue
@@ -237,7 +235,7 @@ func (c *baseClient) cmdTimeout(cmd Cmder) time.Duration {
 func (c *baseClient) Close() error {
 	var firstErr error
 	if c.onClose != nil {
-		if err := c.onClose(); err != nil && firstErr == nil {
+		if err := c.onClose(); err != nil {
 			firstErr = err
 		}
 	}

sentinel.go

@@ -90,9 +90,7 @@ func NewFailoverClient(failoverOpt *FailoverOptions) *Client {
 			opt:      opt,
 			connPool: failover.Pool(),
 
-			onClose: func() error {
-				return failover.Close()
-			},
+			onClose: failover.Close,
 		},
 	}
 	c.baseClient.init()
@@ -391,8 +389,7 @@ func (c *sentinelFailover) listen(pubsub *PubSub) {
 			break
 		}
 
-		switch msg.Channel {
-		case "+switch-master":
+		if msg.Channel == "+switch-master" {
 			parts := strings.Split(msg.Payload, " ")
 			if parts[0] != c.masterName {
 				internal.Logf("sentinel: ignore addr for master=%q", parts[0])