State Design Pattern – Use, Advantages, & Disadvantages


State patter or state design pattern is one of the design patterns introduced by the Gang of four teams. This pattern falls under the category of behavioral design pattern.

In many cases, you might need to design the state machine in your application. A state machine is a very known concept in computer engineering . The state pattern is a way of implementing the state machine using object-oriented fashion.

Table of Contents

What is the state design pattern?
When should we Use the State Model?
What are the Advantages of Using a State Design Pattern Model?
What are the Disadvantages of Using this Model?
Realtime Use cases of State design pattern

UML diagram of State design pattern Participants

Bank account problem statement
Understanding the AccountContext class
Implement the SilverState of the account.
Implement the RedState class
Implement the GoldState class
Enhancements in the given solution

Github link for the project

Hi folks, In this article, we will try to understand the state pattern, what, why and when to use this patter. Also will implement one of the case study using c#.

What is the state design pattern?

The state design pattern is a scheme used to model changes in the state (or states) of an object. It delegates rules for such changes to individual objects representing each possible state.

When should we Use the State Model?

An object with a relatively complex set of possible states applies the state model. Especially applied for an object with multiple business rules on how state transitions occur and what happens next.

In addition, you can update any state at any time with a special logic if the object is merely a state-owned property. This increases a needless complication in the State Schema. However, for the objects representing real-world concepts, with a compound workflow, state structure can be a decent option.

What are the Advantages of Using a State Design Pattern Model?

To begin with, a major advantage of the state model is its capability to minimize conditional complexity. It eliminates the need for it and switches statements on objects with different behavioral requirements, unique to different state transitions. So, representing an object’s state using a finite state machine diagram simplifies the conversion of the diagram into a state design model’s types & methods.

What are the Disadvantages of Using this Model?

A developer needs to write a large amount of code for the state schema. Depending on the number of different defined state transition methods and possible object states, you can write numerous methods. Thus, for N states with M transition methods, the total number of methods required will be (N+1)*M.

An insurance...

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