Design Patterns: Single Responsibility Principle Explained Practically in C# (The S in SOLID)

When you are writing code, are you doing it right? That is a question that worries a lot of people, and it should probably at least be something every developer thinks through. Design patterns are best-practice concepts that we can implement into our code to make it better in some way. Think of them as guardrails that keep our code safe. In this video, we are going to look at the first entry in the famous SOLID principle. The S stands for Single Responsibility Principle. We are going to dive into what it means, how it should change our programming practices, and how far we should take it.
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Source Code: leadmagnets.app/?Resource=SIn...
0:00 - Intro
1:33 - Demo code overview
1:56 - Single Responsibility Principle: SRP explained
5:09 - Implementing SRP: Refactoring demo code
24:38 - Recap
25:28 - Summary and conclusions
29:45 - Why many classes is not a problem for your application
31:29 - How to keep a balance: creating to classes, when to split up a class
33:23 - Concluding remarks

[@jayjayjaythebrand]

Having someone like Tim Corey in the C# community is beyond essential. Thank you for all you do. Greatest C# teacher there is

[@IAmTimCorey]

I appreciate the kind words.

[@Reaper7mk]

Thank you for what you do Tim. You're one of those people that get to the top and throw the ladder down for everyone else. I hope you have a happy life.

[@IAmTimCorey]

You are most welcome. Thanks for watching.

[@StealthFlightFPV]

I appreciate your time spent putting this together. It was very helpful for quick review or teaching this concept to new developers. You are easy to understand because your speak clearly and you explain your thought processes. Well done.

[@IAmTimCorey]

I appreciate the kind words.

[@pacifista2099]

Even when I watch your videos on very basic topics, I always learn something new.

[@IAmTimCorey]

Excellent!

[@21kaduku]

I’ve been learning SOLID this week and I’m really happy I found this.

[@IAmTimCorey]

Excellent!

[@janoslaszlo3272]

"If you have to scroll you've probably done something wrong." I think this statement is a bit exaggerated because it's hard to have small classes in large programs, achievable in small ones. In some cases there is a lot of functionality revolving around a subject and moving code out of the class to keep it small would break another important principle, that is cohesion. I think of classes as nouns and of methods as verbs. In my opinion the single responsibility principle asks us to put the verb/method in the right class/noun. Before starting to write the code for you program, think about the nouns and verbs that are involved in your program and structure your nouns into systems and subsystems, in other words lay out the skeleton of your program.

[@IAmTimCorey]

The problem with long methods is that testing is a mess. If you have one branch in your method, you need to write two tests (one for each side of the branch - simplified, of course, since there may be more than that to write). However, if you have five branches, the number of tests you have to write to fully test things can be exponentially more (not just 10).

[@kenlinder1547]

@@IAmTimCorey Thanks for the video on SRP. I am working on expanding my coding horizons and your videos do indeed help. I must agree with Janos. While I strongly agree with your sentiment to keep classes small, "If you have to scroll, you've probably done something wrong," is is simply not true for non-trivial programs. When I went to college in the late 80's, the rule-of-thumb was that a function, procedure or method should be no longer than a printed page. I try to maintain this guideline while writing new code and refactoring old. However, in more than 50% of the code I handle on a daily basis, this limit is difficult to accomplish. Complex algorithms require complex code at times. Trying to bend a large program into classes that will not scroll, in my opinion would be like watering my garden with a teaspoon. :-) On the other hand, I have literally twitched after first review of an old program with methods that were thousands of lines long. Yes... one method was more than 2000 lines by itself. Debugging was a nightmare. There is one other minor comment... You said nothing about multiple method exit points. To avoid confusion, especially in programs that have been heavily modified by several programmers, maintaining single exit points can be extremely helpful. Thanks again & keep up the great work!

[@ch08532]

Agree. This is excessive. We have an internal rule on methods being more than one scroll but having this policy on classes in just not right. SRP is basically just decomposition of your methods/classes into smaller and discrete units of work. The trick is to not go overboard with it and to find balance.

[@ericritter46]

I've been watching your material for months, now. You definitely made me advance in my skill set.

[@IAmTimCorey]

I'm glad!

[@stevancosovic4706]

This is actually the most comprehensive analysis of SRP examined in practical manner, great video, thanks!

[@IAmTimCorey]

Glad it was helpful!

[@totalnewbie8619]

Hello Mr. Corey. I just found your videos and have found them most helpful. Thank you very much for sharing your knowledge freely and openly with the rest of the world. It is people like you that restore my faith in humanity. Best regards from Mexico.

[@IAmTimCorey]

You are most welcome. Thanks for watching.

[@leriosindane720]

LOL I Scroll On My Visual Studio Like a Book. Thank you for making me realize (in a simple and objective way) how much I have to improve, as a programmer!

[@IAmTimCorey]

You're very welcome!

[@shawnmofid7131]

This is the way to learn programming. Thanks so much.

[@IAmTimCorey]

You are welcome.

[@seva4241]

I know this is an old video series, but I have been searching for a while now for explanations of design patterns, and just anything related to coding really. Trying to get a better grasp of reasoning and how to go about solving problems. You're videos explain things so well. I honestly think these videos have had the biggest impact on my skills over any course/videos I have previously watched. I genuinely thank you for these. You wouldn't happen to have a programming course by chance? lol

[@IAmTimCorey]

I do have a lot of programming courses at iamtimcorey.com. If you are looking for a beginner to advanced C# course then the Foundation in C# course is the right one to start with: www.iamtimcorey.com/p/complete-foundation-in-c-course-series

[@LordShpinaq]

Tim, you deserve a medal, thanks for all your effort

[@IAmTimCorey]

You are most welcome. Thanks for watching.

[@faizalvasaya2998]

- Beautifully crafted explanation of Single Responsibility Principle. - Depth is what I like the most in your tutorials Tim. - Along with the principle, we would also like to hear your personal experiences on SRP. The challenges that you've faced while following SRP in live projects.

[@IAmTimCorey]

I appreciate the kind words. As for my experiences, I'll add that to the suggestion list. In general, my experience is that it really helps make the application easier to maintain. It is hard to do well sometimes and sometime you cheat, but doing it right pays off in the end.

[@WarrenLaFrance]

I think this "A class should have only one reason to change" is what causes a great deal of confusion and finding a means to explain this would most useful.

[@IAmTimCorey]

Yep, that can be tricky to identify clearly.

[@nrnoble]

Of all the videos I have watched on this channel, the Design Pattern series of videos has been the most helpful for me personally, and it explains why teams often fear making even small changes in code, they know that a minor change can easily cause a massive cascading effect. I have been in dev meetings where the decision was made to leave in dead code simply out of the fear that pulling it will have unknown long-term effects, even if all code testing indicates there are no calls being made to the dead code.

[@tomthelestaff-iamtimcorey7597]

Truth! I think I was in some of those same meetings.

[@karreem]

Tim ! You're the best; I learned a lot from you. Thank you for all what you do for us ...

[@IAmTimCorey]

Awesome!

[@RalfsBalodis]

0:00 - Intro 1:33 - Demo code overview 1:56 - Single Responsibility Principle: SRP explained 5:09 - Implementing SRP: Refactoring demo code 24:38 - Recap 25:28 - Summary and conclusions 29:45 - Why many classes is not a problem for your application 31:29 - How to keep a balance: creating to classes, when to split up a class 33:23 - Concluding remarks

[@IAmTimCorey]

Thanks again

[@andreymtrx8368]

Literally, the best videos about solid principles, thank you a lot

[@IAmTimCorey]

You are welcome.

[@Didi-bz6kt]

You have done what many others haven't ! Simple, understandable - user friendly ;) Thank you!!

[@tomthelestaff-iamtimcorey7597]

Thanks for the support and encouragement

[@sputtnick1993]

best practical way of showing SRP and clean oop structure I have seen! Thank you!

[@IAmTimCorey]

Glad it was helpful!

[@pranaygawand4884]

Thanks tim... You never stop to impress your viewers.... Another high quality video...!

[@IAmTimCorey]

Thank you!

[@brendonanderson8673]

You make things so much simpler. Thank you!

[@IAmTimCorey]

You are so welcome!

[@moduntilitbreaks]

Learning C# currently with Unity. Can't thank enough for these videos. Good job!

[@IAmTimCorey]

You are most welcome. Thanks for watching.

[@sibonisozungu1748]

Best SRP video I ever came accross. Thank you Tim

[@tomthelestaff-iamtimcorey7597]

Thanks for watching!

[@neemapranay23]

Thank you so much!! This is what I am looking for. You are a great teacher Tim. Keep creating the awesome content.

[@IAmTimCorey]

You are welcome.

[@thestarinthesky_]

Thank you. Great explanations! Finally have found the SOLID principles tutorials where youtuber doesn't want to demonstrate how intelligent they are by introducing too complex examples that make learners/viewers even more confused than before!

[@IAmTimCorey]

Glad it was helpful!

[@damienk777]

Incredible, recently I've spent a some of my time researching/learning new design patterns. Few days later, just when I needed it the most, this video appeared. Not too long ago I was struggeling with Unit testing and the same thing happened! Your timing with your videos just couldn't be better! Thank you so much for creating these educative videos for us over the years. I realy appreciate your efford.

[@IAmTimCorey]

Excellent. Well, there are more design patterns coming. I will finish out SOLID first but then I will be covering other patterns as well. I am not sure when the videos will come out yet. I am still working on my production calendar. I have so many videos I want to get out but I need the time to get them done. I am not done covering unit testing yet (I will be covering mocking next) and I am almost done the prep work for my .NET Core series too. Plus, if you are on my mailing list you know there are even more things coming that I can't wait to get out the door.

[@damienk777]

I wish you good luck!

[@BulbulAhmedju]

Your information providing technique is awesome. You make things clear and simpler. Thank you very much !!!

[@IAmTimCorey]

You're very welcome!

[@akashbhardwaj1535]

Perfect for beginners, for professional a quick basic recap. I highly recommend this tutorial

[@IAmTimCorey]

Thank you!

[@kamalbalasubramanian621]

This is the best and clear explanation with example that I have seen in the Internet, Kudos!!

[@IAmTimCorey]

Thank you very much.

[@sanmathi3968]

I'm really lucky to find your videos here. I got my internet and curiosity back after watching your videos. I promise i won't miss any of your videos and thank you so much for sharing your knowledge..great ful to you❤❤

[@IAmTimCorey]

You are welcome.

[@machi992]

Best explanation of SRP I have ever found. I have been trying to understand SOLID better, but it has been very hard for me, specially because english is my second language. I also appreciate that you use easy examples and explain very well what you are doing. Some examples online are really advanced and I don't have a clue what the code is even doing.

[@IAmTimCorey]

I am glad it was so helpful to you.

[@eduardocarvalho4232]

Very well explained, unhurried and very detailed, I had been looking for content of this type for some time. Thanks for the knowledge and availability Tim! 👋

[@IAmTimCorey]

Glad it was helpful! Please consider checking out my other videos - kzbin.info/door/-ptWR16ITQyYOglXyQmpzw

[@ladanzahir]

Thanks so much for the amazing playlist. You are saving my life :)

[@IAmTimCorey]

You are most welcome. Thanks for watching.

[@MrSudheer506]

Hi @IAmTimCorey, I wanted to express my gratitude for your insightful videos. They serve as a valuable reference for individuals preparing for interviews or seeking to refresh their fundamentals Thank you for your outstanding work!

[@IAmTimCorey]

I appreciate the kind words.

[@MrAngel750]

This is Perfect, straight forward and clear explanation.

[@IAmTimCorey]

Thanks

[@blackbarry45]

great video and explanation! Much better to see and go through code THAN some powerpoint presentation. This kind of teaching is much more enjoyable

[@IAmTimCorey]

I am glad you found it so valuable.

[@hippiestafarii]

I forgot to thank you for this playlist ... very well explained !!!

[@IAmTimCorey]

You are most welcome. Thanks for watching.

[@djangounchained7314]

Amazing tutorial!!! I have to learn SOLID and I think I did it on the PERFECT WAY!!! I will go through the whole course and then watch all your other content

[@IAmTimCorey]

Thank you!

[@MR2SpyerJournal]

Very good. I've heard the lecture from "uncle Bob" himself on KZbin, but he never went over the application of the principles. This is helpful. Thanks.

[@IAmTimCorey]

I am glad it was helpful.

[@steliosvasiliadis3480]

I changed it and i really like it the way i did it, thank you Tim!

[@IAmTimCorey]

Great job!

[@sidisidahmed755]

Man i hope you are teaching college or somewhere cause it fits you so much , much love brother u the best !!!!!!

[@IAmTimCorey]

Not anymore. I teach on iamtimcorey.com now.

[@lycagos1278]

may you live a thousand years, you and your family, these videos are unique and extremely useful

[@IAmTimCorey]

I am glad you found them valuable.

[@LockViles]

day 3 on learning C#, my first language and was thinking of what this principle might be called. a few peeps told me single responsibility and your video was the first that showed up. im glad i watched it! thank you!

[@IAmTimCorey]

Great! Hey, if you are just starting out in C#, I put together a video on how to set up your C# learning path to learn things in an order that makes sense and fills in the gaps: kzbin.info/www/bejne/gobZY2OHrb2dnNk

[@VideoWarfare]

Tim I can’t thank you enough for this video! I’m so glad I found your content! I’m just a bit confused on the .Substring(1,0) method, but that’s probably because this video was more about design concepts/OOP. Still learned so much!

[@shaunhunterit342]

He created the username TCorey, so that requires just the first letter of the first name. It's Substring(0, 1) not (1, 0). 0 is the startindex and 1 is its length.

[@longuinni]

Thank you Tim for sharing your knowledge and experience

[@IAmTimCorey]

You are welcome.

[@SrinubabuRavilla]

Well explained Tim Corey. Thank you for the beautiful video.

[@IAmTimCorey]

You are welcome.

[@IAmTimCorey]

Thank you!

[@tonyfearn5350]

Perfect explanation! I never learn from power point diagrams, but in this one tutorial, I can already see where I have gone wrong in the past, and how I can improve existing code and create new code in the future, thanks

[@IAmTimCorey]

Excellent!

[@tccoder3547]

Corey, Thank you for this video. The SRP principle helped me understand that the class should only perform one job. It also help me under the function of the main method. It should be the "guide" or "legend" sort of speak to my application. This is good for me . Thank again

[@IAmTimCorey]

Glad it was helpful!

[@pierreplourde]

Excellent video. I’d always thought of SRP in relation to methods, but seeing it applied to classes as well was an eye opener. Definitely the better way.

[@IAmTimCorey]

Glad it was helpful!

[@broski1491]

This Is very good, I always used classes, but thanks to this video, now I can make my code readable and easy to rewrite. I did what you did In this video sometimes, but you gave me a better view and few points, some stuff I never did, appreciate It. Thanks Tim.

[@IAmTimCorey]

That's great!

[@fernandoluz891]

Congrats Tim, I really enjoyed your way to present SOLID. Very clean and simple way. In the first moment I thought this video is too long, but now I understand you go step by step in the explanation and this make sense. I will watch the other videos. Congratulations again :-)

[@IAmTimCorey]

Glad it was helpful! My goal is to educate, not just dump out information. For some that seems to be too much information, but I am glad you see the value and benefit of it. Thanks for the feedback.

[@CindyLatta]

That was brilliant. Thanks Tim

[@IAmTimCorey]

You are welcome.

[@iandalrymple7255]

I totally and completely agree with the practical approach to your teaching. For me personally, the theory comes into focus later when I have some chops practically doing the things around which the theory is built. Thanks for the videos sir - they are excellent.

[@IAmTimCorey]

You are welcome.

[@ivoavido1]

Same! Too many times we see tutorials teaching solutions for problems we haven't encountered yet

[@khanfaizan05]

Tim you are a very great teacher.. I learnt a lot from your videos. Thank you so much. You are really an inspiration for me to learn.,👍👍

[@IAmTimCorey]

You are very welcome!

[@TheChodex]

Thanks for these lessons Tim! As a student from college these SOLID principles are somewhat of a game changer for me!

[@IAmTimCorey]

Excellent! I'm glad they helped.

[@SaiGame]

People keep complain about I have so many classes for simple job. You just make my life more easier, thx bro

[@IAmTimCorey]

Awesome!

[@colinmiddleton8127]

Hi @IAmTimCorey , firstly thank you for these helpful videos. I'm writing an application that takes data from one system, translates it into a different format, then passes it to another system. I'm holding the in transit data is a sinle class, with subclasses to represent the sub lines of the data. Currently the class is over 3,000 lines. We've got a load of local variables to hold the data, propeties for each variable (includ a check not null and error handling), then there are half a dozen constructors, accepting different types of data input. Next, we have a block of methods for easily navigating the sub classes (again each has only a couple of functional lines, then the try-catch stuff around it. Obviously the methods alone require scrolling to veiw them all and some of the constructors won't fit on a single screen (there might be almsot 100 fields in the data element that we're passing. How should the above be restructured to work with the SRP concept, please? Especially regarding not having to scroll to see the whole class?

[@paragraut3504]

Your videos are awesome and inspiring, keep making these videos. It helped me made my code lot cleaner

[@IAmTimCorey]

Will do! I'm glad you are getting a lot of value out of them.

[@raminrasoulinezhad]

Great thanks, easy to understand.

[@Will-do8rl]

Love the way you explained it!!!

[@IAmTimCorey]

Thanks!

[@israell9320]

love your content and how you make our lives a lot easier

[@IAmTimCorey]

Thanks!

[@jasper5016]

This is the best way to keep the projects going for years :D Jokes apart. Tim, I am a big fan of your videos. I have an interview next week and I hope I will pull that off.

[@IAmTimCorey]

Good luck!

[@ceralguy85]

Very simple and clean explanation and at the end the patterns are to write a good quality and maintaneble code

[@IAmTimCorey]

Thank you!

[@nana86swee90]

I've always love your explanation, easy to understand

[@IAmTimCorey]

Glad you like them!

[@sharathgoud1573]

Thank you Tim.. Respect from India

[@IAmTimCorey]

You are welcome.

[@Vindisify]

I always disliked opening my old projects because I know the horror I will face trying to change something, this explains so much. I think it's time to revisit some old projects and try to apply this now. Thank you Tim.

[@IAmTimCorey]

You are welcome.

[@unroot3471]

Wow, really well explained. Our class recently got introduced to SRP, and this is the ideal video, which ACTUALLY explained SRP in a nutshell. Thanks again!

[@IAmTimCorey]

Glad it was helpful!

[@johnkurien5485]

Rahul Bhai kyaa haal h?

[@unroot3471]

Arre, bhai! big fan sir!

[@mohamadhelaly4979]

Thanx alot. So simple clear and clean. Thanx again. Please keep goooooing

[@IAmTimCorey]

You are welcome. I can't wait to get the next one out the door.

[@TundeAjao]

Tim you are really doing great stuff!! Thanks and God bless

[@IAmTimCorey]

Thanks!

[@irriet2]

Good, clear explanation. Thank you.

[@IAmTimCorey]

You are welcome.

[@enriquellerena4779]

You are a great teacher thanks for your tutorials

[@IAmTimCorey]

You are welcome.

[@ahmedEchch]

Now the SRP is clear, Thanks Tim for your effort (y)

[@IAmTimCorey]

Great!

[@vijaykalaiselvan]

Now I really understood the SRP, Thanks

[@IAmTimCorey]

Awesome!

[@rakeshg277]

A really great video, thank you for sharing it with us.

[@IAmTimCorey]

You are welcome.

[@dhruvpanchal9010]

Congratulations Tim for 200K Subs. Stat SOLID ! :D

[@IAmTimCorey]

Thanks!

[@fatimaajij428]

Your tutorials are amazing. thanks for uploads

[@IAmTimCorey]

You are welcome.

[@compoundsound]

Thank you, I'm finally understanding.

[@IAmTimCorey]

You are welcome.

[@aaen9417]

Thanks for these videos Tim.

[@IAmTimCorey]

You are most welcome. Thanks for watching.

[@prashantaganguly]

Good explanation with good example. Thanks

[@IAmTimCorey]

You are welcome.

[@girishkamalapur]

Clear and crisp.

[@IAmTimCorey]

I'm glad.

[@nikolakaric3784]

Excellent video! Thanks!

[@IAmTimCorey]

You are welcome.

[@ChengZhangWhyNot]

Thanks for the good simple video! Tim

[@IAmTimCorey]

You are most welcome. Thanks for watching.

[@BoilermakerRV]

This video reminds me of a conversation I had with a colleague. He was frustrated with the fact that a Matlab script we were using made numerous references to other files (i.e. methods or classes). I knew at the time that “that’s how programming is done”, but after videos likes this I could have defended the practice much more fervently.

[@IAmTimCorey]

I am glad my content is helpful to you.

[@kenjiobara]

I loved the explanation ! Great video!

[@IAmTimCorey]

Thanks!

[@thestarinthesky_]

Absolutely amazing! Thanks for sharing

[@IAmTimCorey]

You are welcome.

[@sherifmankarious88]

This is awesome - thanks Tim!

[@tomthelestaff-iamtimcorey7597]

Thanks for trusting Tim for your training.

[@KaushikGanguly72]

Thanks for the post, helped me to clear my doubts.

[@IAmTimCorey]

Glad it helped!

[@slipsoon8864]

Thank you Tim for such a great video! It really helps understand the SRP design principle =)

[@IAmTimCorey]

You are welcome.

[@GunaNidhiPokhrel]

Great So easy to understand good approach Tim you rocks.

[@tomthelestaff-iamtimcorey7597]

Thanks for trusting Tim

[@PunamchandBadwaik]

Well explained... Thanks a lot Tim for awesome videos ☺️👍

[@IAmTimCorey]

You are most welcome. Thanks for watching.

[@Jsarna5]

I have a controller class which is basically 1000 lines of codes. It's time i start using SOLID principles effectively from now on because testing has being real struggle for me. Thankyou for this amazing series Tim :)

[@IAmTimCorey]

That will definitely give you a lot of benefits.

[@oneanddone7992]

Superb video. Thank you.

[@IAmTimCorey]

You are welcome

[@disondavis]

Thanks for detailed explanation.

[@IAmTimCorey]

You are welcome.

[@vidyasagarpamula794]

Hey Tim...can't wait to watch rest of the videos ..(sOLID)...

[@IAmTimCorey]

Open/Closed Principle should come out on Monday.

[@HawkEyeExplorers]

Great explanation. Thank you

[@IAmTimCorey]

You are welcome.

[@lucianosantillan164]

Genio! Gracias por recomendarme estos vídeos por e-mail!

[@IAmTimCorey]

I am glad they were helpful!

[@essamadam6964]

Thanks for that wonderful explanation

[@IAmTimCorey]

You are welcome.

[@swingymcswing]

Thank you so much , Tim. I'm re-entering the sw dev field and this is just what I needed. I'm going to watch all your SOLID videos, reading about SOLID is to me, pretty boring. Seeing the code though, makes it all clear. Subscribed.

[@IAmTimCorey]

Awesome!