The Object Orientation in Go

Summary on object orientation

Let us summarize what we have seen about object orientation in Golang so far: Go has no classes, but instead, it has loosely coupled types and their methods to implement interfaces. The three important aspects of OO-languages are encapsulation, inheritance, and polymorphism. How are they realized in Go?

• Encapsulation (data hiding): in contrast to other OO languages where there are four or more access-levels, Go simplifies this to only two levels:
  • package scope: object is only known in its package, it starts with a lowercase letter
  • exported: object is visible outside of its package because it starts with an uppercase letter. A type can only have methods defined in its package.
• Inheritance: via composition that is embedding of 1 (or more) type(s) with the desired behavior (fields and methods); multiple inheritance is possible through embedding various types.
• Polymorphism: via interfaces in which a variable of a type can be assigned to a variable of any interface it implements. Types and interfaces are loosely coupled; again, multiple inheritance is possible through implementing various interfaces. Go’s interfaces aren’t a variant on Java or C# interfaces, they’re much more. They are independent and are key to large-scale programming and adaptable, evolutionary design.

So in effect, we can say that Go implements all important object-oriented features.

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Even without classes and inheritance, Go has managed so well to be an object-oriented language. There is a quiz in the next lesson for you to solve.