golang定义func类型

如下，定义一个DecodeFunc类型，DecodeFunc是一个func([]byte, PacketBuilder)类型，可以通过d(data, p)调用

type DecodeFunc func([]byte, PacketBuilder) error

// Decode implements Decoder by calling itself.
func (d DecodeFunc) Decode(data []byte, p PacketBuilder) error {
	// function, call thyself.
	return d(data, p)
}

// DecodePayload is a Decoder that returns a Payload layer containing all
// remaining bytes.
var DecodePayload Decoder = DecodeFunc(decodePayload)
func decodePayload(data []byte, p PacketBuilder) error {return nil}