How Can Polymorphism be Achieved in Go Without Traditional Inheritance?

Polymorphism in Go lang: Achieving Through Interfaces and Composition

Polymorphism, a fundamental concept in object-oriented programming, allows objects to behave differently based on their class or type. In Go, unlike traditional OO languages, polymorphism is achieved through interfaces and composition.

Problem:

An attempt to implement polymorphism in Go using structural inheritance like the following code snippet would result in an error:

<code class="go">type Foo struct {
   ...
}

type Bar struct {
   Foo
   ...
}

func getFoo() Foo {
   return Bar{...}
}</code>

Solution:

In Go, polymorphism is achieved through interfaces and composition. An interface defines a set of methods that a type must implement, allowing the type to be used polymorphically anywhere the interface is expected.

The code below demonstrates how polymorphism can be achieved in Go using interfaces and composition:

<code class="go">package main

import "fmt"

type Foo interface {
   printFoo()
}

type FooImpl struct {

}

type Bar struct {
   FooImpl
}

type Bar2 struct {
   FooImpl
}

func (f FooImpl) printFoo() {
    fmt.Println("Print Foo Impl")
}

func getFoo() Foo {
   return Bar{}
}

func main() {
    fmt.Println("Hello, playground")
    b := getFoo()
    b.printFoo()
}</code>

In this code snippet:

• Foo is an interface that defines a method printFoo.
• FooImpl is a concrete implementation of the Foo interface.
• Bar and Bar2 are structs that embed the FooImpl type and implement the Foo interface indirectly.
• getFoo() returns an instance of Bar as type Foo, demonstrating polymorphism.

By utilizing interfaces and composition, Go provides a flexible and efficient approach to achieving polymorphism without the need for traditional inheritance.

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