Creational Design Patterns
Creational design patterns deal with object creation mechanisms. These patterns abstract the instantiation process, making a system independent of how its objects are created, composed, and represented.
This is useful when the system should not depend on the way objects are instantiated or when the instantiation process is complex.
When to Use Which Creational Design Pattern
| Creational Pattern |
Use Case |
| Singleton |
Use when only one instance of a class should exist globally (e.g., logging, database connection). |
| Factory Method |
Use when a class delegates the responsibility of creating objects to its subclasses or separate methods. |
| Abstract Factory |
Use when you need to create families of related objects without specifying their concrete classes. |
| Builder |
Use when constructing an object step by step is required, especially when the creation process is complex or requires multiple optional fields. |
| Prototype |
Use when the cost of creating an object is expensive or complex, and you can create a prototype of the object and clone it. |
Most Commonly Used Creational Design Pattern
The Singleton pattern is the most commonly used creational design pattern. It ensures that a class has only one instance and provides a global point of access to it. This is particularly useful in scenarios like managing database connections, logging mechanisms, or configurations that should be shared across the system.
Pros and Cons of Creational Design Patterns
Pros
- Improves flexibility and reusability by decoupling object creation from the client code.
- Encapsulates complex object creation logic, making the code easier to manage and maintain.
- Ensures that objects are created in a controlled and consistent manner (e.g., Singleton).
- Supports complex object construction (e.g., Builder) or creating multiple related objects (e.g., Abstract Factory).
Cons
- Can add complexity to the design due to extra layers of abstraction.
- Some patterns (like Singleton) can be difficult to unit test because they introduce global states.
- Overuse can lead to an overly complex and hard-to-understand codebase.
List of Creational Design Patterns
- Singleton Pattern Ensures a class has only one instance and provides a global access point to that instance.
- Factory Method Pattern: Defines an interface for creating objects but allows subclasses to alter the type of created objects.
- Abstract Factory Pattern: Provides an interface for creating families of related or dependent objects without specifying their concrete classes.
- Builder Pattern: Allows constructing complex objects step by step, separating the construction process from the representation.
- Prototype Pattern: Allows copying existing objects without making the code dependent on their classes.