Understanding Brackets After func in Go Methods

In Go, you may encounter brackets following a func keyword. These signify a method, not a function. Let's understand this feature with a specific example:

func (v Version) MarshalJSON() ([]byte, error) {
  return json.Marshal(v.String())
}

Here, we have a method named MarshalJSON attached to the Version struct type. The syntax:

• (v Version): This part represents the method receiver. For methods, the first parameter is always the receiver value. Here, v represents an instance of the Version struct.
• func: Indicates that this is a method.
• MarshalJSON(): The method name, followed by its signature.

So, in this example, the MarshalJSON method of the Version struct converts its string representation to JSON.