Introduction to Design Patterns

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In this tutorial we will discuss
1. What are Design Patterns
2. Evolution of Design Patterns
3. The three categories of design patterns

Text version of the video

Slides

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In many interviews you might have encountered lot of questions related to interfaces, abstract classes, delegates and other features related to object oriented programming along with the design pattern related questions.

Design patterns solutions are evolved from the features of object oriented programming.

Once you understand the design patterns, it makes you very comfortable in attending interviews as well as applying these features with confidence in your projects or applications.

Implementing design patterns in the applications are proven and tested. Writing the code aligning with design patterns will make your applications Reliable,Scalable and Maintainable.

What are Design Patterns
Design patterns are reusable solutions to the problems that we encounter in the day to day programming. They are generally targeted at solving the problems of object generation and integration. In other words, Design patterns acts as templates which can be applied to the real-world programming problems.

History and evolution of design Patterns
The four authors of the book famously know as Gang of four are the ones who brought the concepts of design patterns in their book “Elements of reusable Object-Oriented software” .

Gang of Four has divided the book into two parts with first part explaining about the pros and cons of object oriented programming and the second part describes the evolution of 23 classic software design patterns.

For more details, please refer to the following wikipedia article

Types of Design Patterns
Gang of Four have categorised the design patterns in to 3 types based on different problems encountered in the real world applications. They are Creational, Structural and Behavioural.

Creational design patterns : These patterns deal with object creation and initialization. Creational pattern gives the program more flexibility in deciding which objects need to be created for a given case.

Examples of Creational design patterns category : Singleton , Factory and Abstract Factory etc.

Structural design patterns : This pattern deals with class and object composition. In simple words, This pattern focuses on decoupling interface, implementation of classes and its objects.

Examples of Structural design patterns category : Adapter, Facade and Bridge etc.

Behavioural design patterns : These patterns deal with communication between Classes and objects.

Examples of Behavioural design patterns : Chain of Responsibility, Command and Interpreter etc.

For understanding design patterns better it is very important to have basic knowledge about the following object oriented concepts
1. Abstraction
2. Inheritance
3. Polymorphism
4. Encapsulation
5. Interfaces
6. Classes
7. Abstract classes

In Part 2 we will focus on the Singleton design pattern in detail with a simple example.

[dhawalkasar]

Thanks Avesh for great tutorial, BTW Who else is looking for Kudvenkat sir? I love his voice.

[tamchau]

This is a very important principle in OOP -Venkat would be a great person to do this tutorial

[saransh]

Finally you have started making videos on design patterns. thank you so much.

[dhawalparmar]

My favourite channel of dotnet technology

[venkatpalllantla]

Thanks for coming up with design patterns. Appreciate your effort pragim technologies. But missing Venkat's voice very badly. please keep posting the videos. You guys are doing great job.

[sahilsehgal]

Felt very good to see a tutorial on this.
Please don't stop this course in mid.
Waiting for next video. :)
Thank you for all your efforts.

[Kifter]

There's a good chance Kudvenkat, having been chipping away making all these videos year on year is actually a pretty busy and successful guy and has passed the torch so to speak to this next guy. Let's give him a chance before we start rabbling that we want the original Kudvenkat.

[balasubramanits]

Avish is doing a good job. I could feel as Venkat. You guys are doing great. Keep going

[binayakgshankar]

This channel is an improved version of NPTEL. Seriously !

[mustafatuncer]

Thank you ver much for preparing this amazing tutorial video. I expect the next.

[umairrazzaq]

He is uncle of kudvenkat. Please focus on lecture. Thanks

[ShubhamJain-dobw]

I love to hear Kudvenkat's voice. I know it does not make sense while learning but still. 🙂

[MaheshPullagura]

Thank you for video on Design Patterns, please continue on these. Appreciate your effort pragim technologies.

[MuhammadArif-rvmy]

This is great stuff explain with very simple examples.
I would appreciate if you could add the tutorial for following design patterns:
1. Repository Pattern
2. Command Pattern
3. Chain of Responsibility

[charlesbaldo]

Nice to see some other people too. The series was helpful

[navmaurya]

Thank you so much Venkat for uploading design pattern series.

[aaronaaronaaron]

So great team! Let's start! THANKS again

[jeewanintube]

Thank you, Thank you, Thank you, .Finally my request is listened.
But Missing Kudvenkat sir.

[shalyamishra]

Excellent Pragim technologies. I am eagerly waiting for this video series, please continue this. Thanks a lot.

[AnywhereAashu]

Thanks, Venkat and Avesh Please upload all videos as soon as possible