Proxy Design Pattern in C#

The Proxy Design Pattern is a structural design pattern. that provides a surrogate or placeholder for another object to control access to it.

This pattern comes in handy when we want to add an extra layer of control over the access to an object, such as lazy loading, access control, or logging. In C#, the Proxy Design Pattern is commonly used to create a surrogate object that represents another object.

We can also say that the Proxy is the object the client calls to access the real object behind the scene. Proxy means in place of or on behalf of. That means, In the Proxy Design Pattern, a class represents the functionality of another class.

Component of Proxy Design pattern

• Subject: This is an interface that defines the members that will be implemented by the RealSubject and Proxy class so that the Proxy can be used by the client instead of the RealSubject. In our example, it is the ISharedFolder interface.
• RealSubject: This is a class that we want to use more efficiently by using the proxy class. This class should implement the Subject Interface. In our example, it is the SharedFolder class.

Composite Design Pattern in C#

The Composite Pattern is a structural design pattern that enables us to treat individual and group objects uniformly by creating a hierarchical (tree-like) structure of objects, where both the composite (groups) objects and leaf (individual) objects share a standard interface.

This pattern lets clients treat individual objects and compositions of objects uniformly. That means the client can access the individual objects or the composition of objects in a uniform manner. It’s useful for representing hierarchical structures such as file systems, UI components, or organizational structures.

What are Composite and Leaf classes?

1. The Composite Class — represents a group of objects and can contain other objects (i.e. env_item_collection, env_item_collection_parent, env_root), and
2. the Leaf Class — represents an individual object that cannot contain other objects (i.e. env_item).

Facade Design Pattern in C#

Facade is a structural design pattern that provides a simplified interface to a library, a framework, or any other complex set of classes.It helps encapsulate the complexity of multiple subsystems into a single unified interface.

In software terms, Facade pattern hides the complexities of the systems and provides a simple interface to the clients.

This pattern involves one wrapper class which contains a set of methods available for the client. This pattern is particularly used when a system is very complex or difficult to understand and when the system has multiple subsystems.

Component of Facade Design Pattern

• Complex System: A library of subsystems.
• Subsystems: These are classes within a complex system and offer detailed operations.
• Façade: This is a wrapper class which wrapper class which contains a set of members which are required by the client.
• Client: This is a class which calls the high-level operations in the Façade.

Decorator Design Pattern in C#

The Decorator Design Pattern is a structural pattern in software development that allows behavior to be added to individual objects, either statically or dynamically, without affecting the behavior of other objects from the same class.

The idea of the Decorator Pattern is to wrap an existing class, add other functionality to it, then expose the same interface to the outside world. Because of this our decorator exactly looks like the original class to the people who are using it.

It is used to extend or alter the functionality at runtime. It does this by wrapping them in an object of the decorator class without modifying the original object. So it can be called a wrapper pattern.

Components of Decorator Design Pattern

• Component: It defines the interface of the actual object that needs functionality to be added dynamically to the ConcreteComponents.
• ConcreteComponent: The actual object in which the functionalities could be added dynamically.
• Decorator: This defines the interface for all the dynamic functionalities that can be added to the ConcreteComponent.
• ConcreteDecorator: All the functionalities that can be added to the ConcreteComponent. Each needed functionality will be one ConcreteDecorator class.

Adapter Design Pattern in C#

The Adapter Design Pattern is a structural pattern that allows incompatible interfaces to work together. It acts as a bridge between two incompatible interfaces, enabling them to collaborate seamlessly without modifying their existing code.The adapter plays the role of converter or translator.

This pattern is particularly useful when integrating new components or systems that have different interfaces from the ones already in use.

To handle the incompatibility, we use different approaches, and based on that, we can classify the Adapter Pattern into 2 parts.

• Object Adapter Pattern
• Class Adapter Pattern