The prototype design pattern is a popular design pattern in software development that allows for the creation of new objects by copying pre-existing objects. This pattern is useful in situations where creating a new object from scratch is either impractical or inefficient.
The prototype design pattern involves creating a prototype object that serves as the blueprint for creating new objects. When a new object is needed, the prototype object is cloned, and the clone is then customized to meet the specific needs of the new object. This eliminates the need for creating a new object from scratch, which can be time-consuming and resource-intensive.
Another advantage of the prototype design pattern is that it allows for greater flexibility in object creation. Since the prototype object serves as the blueprint for creating new objects, developers can easily modify the prototype object to meet the needs of different projects. This allows for a more modular and reusable approach to object creation, which can be beneficial for large-scale software development projects.
The prototype design pattern involves creating a prototype object that serves as the blueprint for creating new objects. When a new object is needed, the prototype object is cloned, and the clone is then customized to meet the specific needs of the new object. This eliminates the need for creating a new object from scratch, which can be time-consuming and resource-intensive.
Another advantage of the prototype design pattern is that it allows for greater flexibility in object creation. Since the prototype object serves as the blueprint for creating new objects, developers can easily modify the prototype object to meet the needs of different projects. This allows for a more modular and reusable approach to object creation, which can be beneficial for large-scale software development projects.
Imagine a company with three office locations that wants to create a directory of employees and the offices they work at. To do this, we can use the prototype design pattern by creating an Employee class and an Address class. As an example, let's consider how these classes might be implemented.
First, we will start with the `Employee` class:
First, we will start with the `Employee` class:
Next, the `Address` class:
Let's first examine how copying an instance of the Employee class could result in problems before implementing the Prototype design pattern.
🚨 🚨 🚨
What happened to Sara? I thought she was a Project Manager at the San Francisco office. However, when Jon made a copy of a class object, the data was passed by reference instead of value, which resulted in Jon overwriting Sara's information.
To solve this issue, we will implement a protocol called `Copyable` that both of our classes will conform to. We will then explore three different options for creating a clone of an object by copying the current one.
When implementing the `init` method, both the `Employee` and `Address` classes must be implemented with the `required init` keyword.
Before we examine an example of the `required init` method, let's create static constants for the three offices to use instead of instantiating the `Employee` class each time as in the first example.
Now, we can copy the `Employee.prototypeSanFranciscoOffice` and customize it to our needs:
This approach allows for the creation of new Employee objects in a more efficient and flexible way, using the prototype design pattern.
Option 2 involves the use of the `associatetype` keyword. If you are unfamiliar with this keyword, please refer to my previous blog post which provides in-depth explanation.
Here is an example of how to use the `clone2` method to make a deep copy the employee instance:
You may have noticed that the cloning methods are functioning correctly, but it can be inconvenient to have to set the properties separately each time. Wouldn't it be more efficient to set the properties within the cloning method itself?
First, let's create an `enum` to list the properties for the class. This will help us avoid any mistakes in spelling string literals and allow us to easily select from the available `enum` cases.
Here is an example of using the clone3 method to create a deep copy of an employee instance, with the option to pass in as many or as few parameters as needed:
In conclusion, the Prototype design pattern is a useful and efficient way to create new objects by copying existing objects. It allows for the creation of new objects without the need for costly and time-consuming processes such as initialization or setup. By implementing the Prototype design pattern, you can easily and quickly create new objects that are ready for use. Whether you're working on a small project or a large-scale application, the Prototype design pattern can be a valuable tool in your software development toolkit.
