5 Ways to Implement The Singleton Design Anti-Pattern in C#

The singleton design pattern helps to limit instantiation of a class to a single object.

A few facts about the singleton design pattern:

• One of the most hated design patterns.
• Erich Gamma would drop the singleton pattern from the Gang of Four book.
• The pattern is easy to misuse.

Due to the last fact, the classic implementation of a singleton is more anti-pattern to me than a pattern.

Let’s see what is wrong with the pattern, how we can mitigate its flaws, and what we can learn from different singleton implementations.

#singleton-pattern #c-sharp-programming #c #cc#

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5 Ways to Implement The Singleton Design Anti-Pattern in C#

The singleton design pattern helps to limit instantiation of a class to a single object.

A few facts about the singleton design pattern:

• One of the most hated design patterns.
• Erich Gamma would drop the singleton pattern from the Gang of Four book.
• The pattern is easy to misuse.

Due to the last fact, the classic implementation of a singleton is more anti-pattern to me than a pattern.

Let’s see what is wrong with the pattern, how we can mitigate its flaws, and what we can learn from different singleton implementations.

#singleton-pattern #c-sharp-programming #c #cc#

Confused With Java Singleton Design Pattern? Have a Look at This Article.

What Is a Singleton Design Pattern?

1. Singleton design pattern allows us to create only one instance of a class and make sure that there exists only one Object in JVM.
2. Singleton class must have a public static method to get the instance of the class from anywhere in the application [from different classes, different packages, etc].
3. Singleton class must have a private constructor to instantiate the object of the class.
4. Singleton class must have a private static variable of the same class which is the only reference of the class[basically this variable will point to only Object of class].

Singleton Design Pattern

All these different implementation methods lead to one goal that is having a single instance of a class at any given point of time in JVM. Let’s see different implementation approaches for the Singleton design pattern

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1. Eager Initialization :

1. This is the simplest implementation of the singleton design pattern class. In this method, the private static variable of the same class [reference] is assigned the object of class at the time of loading the class into the JVM memory.
2. This type of implementation is applicable to the scenarios when we always want the instance of the class.

Let’s see the program to understand this …

package com.vikram;

	public class EagerSingleton {
	    //Only object created when class is loaded and theInstance is private static var pointing to it.
	    private static EagerSingleton theInstance = new EagerSingleton();

	    //private constructor
	    private EagerSingleton(){

	    }
	    //public method to return single instance of class .
	    public static EagerSingleton getInstance(){
	        return theInstance;
	    }
	}

Eager Initialization

#desing-pattern #classloading #singleton-pattern #singleton-design-pattern #java-singleton-pattern

Builder Design Pattern

What is Builder Design Pattern ? Why we should care about it ?

Starting from **Creational Design Pattern, **so wikipedia says “creational design pattern are design pattern that deals with object creation mechanism, trying to create objects in manner that is suitable to the situation”.

The basic form of object creations could result in design problems and result in complex design problems, so to overcome this problem Creational Design Pattern somehow allows you to create the object.

Builder is one of the** Creational Design Pattern**.

When to consider the Builder Design Pattern ?

Builder is useful when you need to do lot of things to build an Object. Let’s imagine DOM (Document Object Model), so if we need to create the DOM, We could have to do lot of things, appending plenty of nodes and attaching attributes to them. We could also imagine about the huge XML Object creation where we will have to do lot of work to create the Object. A Factory is used basically when we could create the entire object in one shot.

As **Joshua Bloch (**He led the Design of the many library Java Collections Framework and many more) – “Builder Pattern is good choice when designing the class whose constructor or static factories would have more than handful of parameters”

#java #builder #builder pattern #creational design pattern #design pattern #factory pattern #java design pattern

Singleton Design Pattern in Modern C++

In software engineering, Creational Design Patterns deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. The basic or ordinary form of object creation could result in design problems or added complexity to the design. In this article of the Creational Design Patterns, we’re going to take a look at the much-hated & commonly asked design pattern in a programming interview. That is Singleton Design Pattern in Modern C++ which criticizes for its extensibility and testability. I will also cover the Multiton Design Pattern which quite contrary to Singleton.

The code snippets you see throughout this series of articles are simplified and unsophisticated. So you often see me not using keywords like override, final, public(while inheritance) just to make code compact & consumable(most of the time) in single standard screen size. I also prefer struct instead of class just to save line by not writing “public:” sometimes and also miss virtual destructor, constructor, copy constructor, prefix std::, deleting dynamic memory, intentionally. I also consider myself a pragmatic person who wants to convey an idea in the simplest way possible rather than the standard way or using Jargons.

Note:

• If you stumbled here directly, then I would suggest you go through, “What Is Design Pattern?” first, even if it is trivial. I believe it will encourage you to explore more on this topic.
• All of this code you encounter in this series of articles are compiled using C++20(though I have used Modern C++ features up to C++17 in most cases). So if you don’t have access to the latest compiler you can use https://wandbox.org/ which has preinstalled boost library as well.

Intent

To create one & only one instance of a class at any point in time.

The Singleton Design Pattern ensures that a class has only one instance and provides a global point of access to that instance. This is useful when exactly one object need to coordinate actions across the system. So, essentially, the Singleton Design Pattern is nothing more than specifying a lifetime.

#design patterns #c++ #cplusplus #programming-c

Prototype Design Pattern - Java

Prototype design pattern tutorial

Definition of Prototype pattern

The prototype pattern is a creational design pattern in software development. It is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects.

Where to use the Prototype pattern

If the cost for creating a new object is expensive and costs resources.

#java #design-patterns #code #tutorial #prototype-design-pattern #design pattern