Prototype Design Pattern in Go

1. Definition

The Prototype Design Pattern involves creating objects based on a template of an existing object through cloning. This pattern is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects.

2. Problem Statement

When building large and complex systems, sometimes initializing an object can be very costly, either in terms of time or resources. In cases where objects of a given class can vary, but initializing is costly, you wouldn't want to freshly instantiate a new object each time.

3. Solution

Instead of relying on the “new” keyword to create instances of the object, a prototype object is cloned to generate new instances, thus eliminating the overhead of initializing an object traditionally.

4. Real-World Use Cases

1. When maintaining a list of potential configurations, and objects initialized from these configurations frequently.

2. For tasks like copying large graphics objects, database objects, or objects that consume significant memory or computational resources.

3. In multiplayer games, duplicate characters with similar attributes.

5. Implementation Steps

1. Create a prototype interface that declares a method for cloning itself.

2. Concrete classes will implement this interface.

3. Use the clone method to duplicate the object instead of creating a new one.

6. Implementation in Go

package main
import (
	"fmt"
)
// Step 1: Prototype interface
type Prototype interface {
	Clone() Prototype
}
// Step 2: Concrete type
type ConcretePrototype struct {
	name string
}
func (p *ConcretePrototype) SetName(name string) {
	p.name = name
}
func (p *ConcretePrototype) GetName() string {
	return p.name
}
func (p *ConcretePrototype) Clone() Prototype {
	return &ConcretePrototype{name: p.name}
}
// Client code
func main() {
	prototype := &ConcretePrototype{}
	prototype.SetName("Original Prototype")
	clone := prototype.Clone().(*ConcretePrototype)
	fmt.Println("Original object:", prototype.GetName())
	fmt.Println("Cloned object:", clone.GetName())
}

Output:

Original object: Original Prototype
Cloned object: Original Prototype

Explanation:

1. A Prototype interface is defined with a Clone method.

2. ConcretePrototype struct implements this interface. It has a method Clone that returns a new instance of ConcretePrototype with the same attributes.

3. In the main() function, we initialize a ConcretePrototype, set its name, and then clone it. Both the original and the clone have the same name attribute, demonstrating that the clone is a copy of the original.

7. When to use?

Use the Prototype Pattern when:

1. The classes to instantiate are specified at runtime.

2. Objects of a class can have one of only a few different combinations of state.

3. A system should be independent of how its objects are created, composed, and represented.

4. The initial configuration setup of an instance is more costly than cloning an existing instance.

In essence, the Prototype pattern offers a more efficient and flexible way to duplicate objects, especially when object creation is resource-intensive.