Factory Method Pattern - Design Patterns (ep 4)

[@thekonax5006]

This guy is already speaking in 1.5 speed. You are the best Christopher! Thank you

[@madhusudanratnalu400]

Hehe

[@madhusudanratnalu400]

I could not able to here properly in 1.25x too😄😄

[@andrejuha164]

@@madhusudanratnalu400 you took me my words :)

[@andrejuha164]

@@madhusudanratnalu400 then is not boring.

[@a.nk.r7209]

and here 1i'm watching it in 1.5x

[@kareemjeiroudi1964]

BTW, whenever I need a reference for design pattern, I would actually go back and watch your videos instead of Design Patterns by the gang of four, because you're incredibly good at explaining Object-Orientation concepts. Please keep up your awesome work!

[@tobylifers3390]

This guy's energy is the best.

[@Mitch_Crane]

Thank you Christopher for another helpful explanation on patterns. I cannot imagine how long it takes to edit all these jump cuts. God bless.

[@ChristopherOkhravi]

Thank you for the kind words and the understanding :) It does take a long time ;) :)

[@gurtelem3586]

​@@ChristopherOkhravi You should use jumpcutter to avoid wasting all this time :-) github.com/carykh/jumpcutter

[@AFPinerosG]

Guys! Please read this comment until the end, I know it is long but it will be worth your time if you really want to learn. I love these videos but this video is WRONG! This is a MISINTERPRETATION of the Factory Method pattern. This is NOT the purpose of the pattern, this is a very common misunderstanding. Be careful. I'm telling you this because I'm reading it from the Gang of Four Design Pattern book, I have it in my hand right now. Where did this video go wrong? 1. When it said that the problem this pattern solves is isolating the complexity of the creation. This is NOT the purpose. Isolating the creation of the objects is the responsibility of the Abstract Factory, not Factory Method. 2. When he said that a factory method can return several types of Products. No!! The factory method should return a SINGLE Product type (this is a little lie, but bear with me) The problem that is solved by this pattern is that the Abstract Creator can't know which Concrete Products should be used by each Concrete Creator, so it let's the Concrete Creators define the type of Concrete Product to be used via a factory method, which is an abstract method (Java). Let's say I have a Zoo class (Abstract Creator) and I have multiple types of Zoo: DogZoo and CatZoo (Concrete Creators). I also have the class Animal (Abstract Product) and the classes Dog and Cat (Concrete Products). Also, the Zoo has a List of Animals. OK, so let's say the Zoo has a method SpawnAnimal() that creates a new animal and adds it to the Animal List. But... Wait... Zoo doesn't know which type of animal it should add to the list! Does it add a cat? a dog? a parrot? Zoo can't know! So Zoo says "OK I will define a factory method createAnimal() so that my subclasses can tell me which type of Animal they want to use when I spawn an animal". So the DogZoo will return a dog in that createAnimal() method. The CatZoo will return a cat. Then when the Zoo calls the SpawnAnimal it creates the new animal with its createAnimal function. That's the idea of this method. The ConcreteCreators tell the AbstractCreator which ConcreteProduct to use!!! That's why the definition says "let subclasses define the ConcreteProduct". The purpose is NOT about isolating the creation in a separate Factory class!!! The purpose is NOT to allow switching factories on runtime to change from one behavior to another!!! Now that I have your attention. I lied when I said that the factory method can only return a single type of Concrete Product. There is actually a variation called the "Parameterized Factory Method" but it requires a parameter to tell the Factory Method which type of object to return in case a Concrete Creator is compatible with multiple Concrete Products. Going back to my example it would be something like FarmZoo and CityZoo. The farm zoo is compatible with Dog, Pig and Sheep. The CityZoo is compatible with Lion, Zebra, Hippo and Giraffe. The createAnimal() would now be createAnimal(type). That's it. So now when Zoo wants to spawn a new Animal you can tell it which type of animal to Spawn. But it won't let you spawn an animal that is not allowed. Now about the isolation. The Abstract Factory pattern DOES isolate the creation logic, thus, the clients create the factory and expect the factory to return a desired object to them. In the factory method there is NO client that consumes a factory expecting an object to be returned. In the factory method pattern the client of the factory method is the Abstract Creator!! The abstract creator is literally the class that "consumes" the factory method implemented by the subclasses. In other words, Christopher has created an Abstract Factory in which the Concrete Factories have a single Factory Method. Keep in mind that Abstract Factory can be implemented as a collection of Factory Methods OR as a collection of Prototypes. Please, Guys, I hope you understood this because this is a HUGE misunderstanding in the industry and most Juniors think they understand Factory Method but they really don't, they constantly confuse it with Abstract Factory because even smart teachers get it mixed up. I hope this was clear :) If you didn't understand, my advice is to go and read the Design Patterns: Elements of Reusable Object-Oriented Software book.

[@MorganFreemanIsLife]

@@AFPinerosG omg ur right

[@jvsnyc]

@@AFPinerosG I regret I can only give this one Thumbs up!

[@BleachWizz]

I think I'm understanding why you're such a good teacher. I can't identify how you're doing it, but you manage to move on and explain new things saying the same thing over and over and over again. But everytime you say it there's something new yo realise about it, the way you wrote the script of your videos (or just made them) is amazing.

[@calexito9448]

Yesssss, i love to see the video once again and see that he was explaining the same concept from the beggining but i just did not understand

[@Nex_Addo]

I really appreciate you going through the logic of "Well why wouldn't we just do xyz", "we don't do that because then...". It really helped make it click that it's not just about being able to instantiate different sub-types, it's also about being able to instantiate them in specific, repeatable ways.

[@FionaCat86]

The example in the book confused me to no end, but you described this so clearly. I think the missing piece for me was understanding the power of encapsulating different strategies for object creation. Once I understood that, it all clicked. Thanks so much, I hope you will continue with more tutorials!

[@nikeshdevaki]

Nothing went to my mind when I watched this video for the first time. Then I went back and read this concept on "The Head First Design Patterns" book and then came back here. This time things are very relatable and visualizable. Now I following this method for all the patterns and its very helpful. I suggest the same for beginners.

[@phuctranbao7518]

Please know that you save my and so many others' lives. People, we need to protect this man at all costs!!!!

[@SuperTurboCrash]

The editing in this video gave me heart palpitations.

[@ChristopherOkhravi]

+SuperTurboCrash Terribly sorry about that and I hope you are ok :) But hopefully the information per second ratio was quite high?

[@tomiekk6255]

actually IMO it was pretty good, at least it's easier to not resign, or fall asleep when something is constantly happening. Perfect for my sleepy day like today:P Thanks @Christopher for this vid. I barely can remember when was the last time I was that much into viewing something on design patterns.

[@loganfeiler2412]

I actually found it quite entertaining to watch, partly because of all the jump edits, and the subject content was explained very well.

[@mbesurich]

This is the best explanation of this pattern! What could be better? Personaly for me - to show an example of what different way of creating products can contain different factories. This could help me to understand more clearly the benefit of using factories versus creating straight the products. But anyway, thank you very much for such understandable information delivery!

[@asrajan55]

Excellent, excellent, excellent lecture! Takes the time to introduce, repeat, cite examples, repeat.... No stupid power point slides... Talks to you and uses his hands and mouth to clearly explain...

[@lima1877]

Just a positive comment: would be nice if you could implement these patterns into actual code after the lecture. Please release more videos!!!! Best..

[@ChristopherOkhravi]

Very good point. Thank you. I'll keep videos as priority number one but will indeed try to figure out something for the code. Thanks!

[@pradeeph2000]

May be the coding part could be an assignment for people viewing the video, it could be shared via github link or something.

[@zebcode]

Or maybe each video could be accompanied by a play by play coding session. I think that would give you the choice of learning the theory and then seeing it in action.

[@bwilless1]

Also the book has code and it attempts to lead you down the path so that you code it yourself!

[@malino24-souls]

im currently doing it :) still need to figure out how factory and abstract factory work :D

[@talyakatz8387]

Im a CS student and you explain it 10000x better than my lecture. Thank you!!!!

[@colococolo]

A 100% agree with you on that the example the book gives is rather hard to relate to. Your explanation helped me understand the factory patterns much better. Thanks a lot!

[@shankar7435]

I completely agree with the fact that the book's example is causing more confusion than understanding. Your explanation at 5:35 is legendary and that's all I wanted to understand this pattern. Thanks a ton for that.

[@aniruddhabhattacharjee3729]

I came here after going through the HFDP book and somehow although having gone through the pattern twice, it was not very clear to me. It's a great content, 27 mins worth every second, gives a very clear idea going from top down approach to the design pattern. Very well explained, thank you.

[@FeroChau]

Very clear explanation! When I try to do unit testing, I find that it will force me to use factory pattern. Whenever any instance is instantiated in runtime, it cannot use dependency injection to inject the reference. However, if I use new operator inside the method, I cannot control the instantiation of the instance. Thus, the class cannot be tested in isolation. In this case, I am forced to inject a factory to the class and use the factory to create object. In this way, I could mock the factory and have a full control of the instantiation.

[@ChristopherOkhravi]

Excellent example and explanation. This should have been part of the video :) :) I agree 100%. Thanks for watching.

That's actually an eye-opening example, thanks a lot.

[@AAA-bo1uo]

Lucas Chau , Can we have an example please? Couldn't wrap my head around injecting a factory when a dependenct is injected (or supoosed to be injected?) Sorry.. just didn't make sense. I get the point you are trying to make, just can't see the implementation or design itself :(

[@firstnamelastname4685]

please explain "Whenever any instance is instantiated in runtime, it cannot use dependency injection to inject the reference." if you are free, thanks!!!

[@ringo.gg.]

Dude you are fuckin amazing, I haven't found any other channel that explains and make clear the concept like you did. Hope you make all the g.a.m.m.a patterns on this series, cheers !

[@ChristopherOkhravi]

Thank you! Will do :)

[@pavel2747]

The examples of factory method and abstract factory patterns provided by this book are the most convenient and understandable ones I've ever seen. And I: 1) have seen dozens of them; 2) am not from NY, Chicago etc. I'm not even from USA.

[@shanm4629]

I realized this is the best explanation after watching bunch of other videos on the same topic for couple of days. Thanks for making such a quality video on Factory Method Pattern. At roots I propose to use this when 1. The client program is only interested in what kind of object is required, rather than what exact object is required. Best Example: I need level4 obstacle and not really bother to tell anything more than that. 2. When The client program is more concerned about how they co-relate when they get created more than one. Ex: random Animals are expected rather balanced animals from a Factory. Awesome explanation. Thanks.

[@NoleoTheDog]

Fan of your details and expressions. It can be seen that you do it by heart and how much you love being a teacher.

[@stewiegriffin6503]

without animals and cars there wouldn't be OOP Every try to explain OOP uses animals and cars.

[@kimk.m2428]

Duh! Mammal enough?

[@jason_v12345]

I know, right? And what's funny is that real-world OOP rarely deals with such familiar, real-world abstractions.

[@madsteeez]

without OOP there wouldn't be animals nor card.

[@madsteeez]

@@jason_v12345 I do. I work for Lufthansa Technik. I abstract aircraft engines.. I love it

[@darkoazure9902]

Great catch! But I'm not :)

[@ЮлияВадимовнаОсновская]

I love that you move so much while speaking, it helps me get less distracted THank you for your explanatoin, it was really useful and easy to understand!

[@mahipparekh2167]

I read the book, I see your videos and then I code & make notes. Thank you once again for this treasure of resources. Lots of respect ➕➕

[@neon_code]

I was reading the book and got confused a lot , now I watch your videos first then read the book. Thanks!

[@nishantsingh1453]

The way u hold on to user's attention level is just impressive !!

[@mirzaaqeel]

You are a teacher.... Hats off to your way of explaining and fitting in examples... perfectly....Thanks a lot.

[@obinnaubah9045]

The Asteroid example really helped drive home the point. I'm still not completely clear about a lot of things but I have a lot more clarity. Thank you very much!

[@ANKITRAJPUT-tu2bk]

Brother , you are the best tutor for design pattern , i was facing so much difficulty with Head first , but now i got a new head to make me understand .. Thanks and keep the good work.

[@rohitkalya]

Very much clear and now i understand why you said ... read first "strategy design pattern". Thanks

[@KellsCode]

This man is a true teacher. That's how it's done.

[@kensearle4892]

Thank you! Ex: During the registration of users, 90% of our clients were exactly the same. However, we had a few custom clients who required us to save some extra registration fields and an extra registration page. Instead of giving those clients their own copy of the system, the factory pattern was used to instantiate those custom clients, which was determined by their domain name. I can't take credit for the choice but it was an interesting way to instantiate the custom Registration objects along with the standard Registration object. P.S. There were several different starting pages due to the custom clients, so using the factory pattern helped with code reuse.

[@SavageStyle77]

Looks like you high but I was surprised how clearly you understand what people need to know, what they struggle with - all your examples are TOP. And how clearly you explaied everything! One of the best teachers I ever saw. Recommended!

[@Mohamed-Maghrebi]

WOW MEN , I DON't UNDERTUND GOOD ENGLISH, BUT I LEARNED MANY THINGS IN YOUR VIDEO, YOU HAVE A GIFT OF SHARING IDEAS, THANK YOU

[@Sam-pq2pk]

I come from other videos where everybody is giving great comments however the video is trash. I finally came to the right place where the explanation is actually good. Thank you Chris you should build a Java course someday!

[@mouhssine04]

Hello Christopher, you've really made my day, your explanation is quite stunning, great thanks for you mister, From now on, no confusion anymore about Factory Method Pattern.

[@justai3766]

Your communication style is amazing. The way you explain these concepts is one of the best. Thank you!

[@yanavalasatava9465]

You are amazing and very charismatic (which is important) teacher! For someone who is new to programming and patterns your videos are of a great help! Thank you!

[@abhishekrajbhanu1452]

I admire your ability to use effective and generic analogy to make your audience understand the concept... Just requesting you to post complete video on SOLID principle .

[@ziadesaa8776]

After 7 years still useful and priceless ❤❤😊

[@lapidations]

This was SO much better than the book

[@brunon.8962]

So, this is about "encapsulating" instantiation in a separate class (factory) so you don't have repeat code and/or mix it with code with different purposes. At the end everything is about separating and organizing implementations by using interfaces so nobody gets crazy trying to figure out what a program does. Imagine to read a book without chapters so you have to find each topic by entirely reading the book... No, let's isolate each part (thanks to inheritance, composition, delegation etc.) and put a name on it so we can read, understand and add code. Imagine those early spaguetti code programmers trying not to commit assasination and instead creating OOP and all these patterns.

[@IamMuldeh]

Going to recommend your channel to all of my class mates.

[@thehumblechannel3441]

I really like the way you explain why Factory method is superior than Simple Factory. It really clears the cloud for me

[@aliki212]

Amazing work!Crystal clear explanation, personalized and out of this world editing!I usually put the videos at 1.25 speed to actually keep my ear on them - yours is purely A+!Cheers!!!

[@adewaleayokanmiadeleye2841]

Thanks for creating this video. Certain concepts are difficult to understand if the examples used are relatable to a certain group of people.

[@AC-xx1uo]

Thank you for this!! I’m an absolute beginner with OOP and this is one of the only videos I’ve found that helps it make sense at my level. The visuals and examples are so great. You rock!

[@safakhan8177]

Thank you Christopher! The example of the game development is brilliant! I think I will always keep that bit in mind whenever I hear the term factory.

[@kuntalshah07]

Dude, This is the best design pattern lecture series I saw till now

[@mercury801115]

I finally understood the difference between simple factory and factor method. Thank you!

[@noknata3240]

i love you i love the way you teach you. You make complex notion ease and you english and exemple are simply and basic. good job

[@paraspatel5763]

This was by far the best explanation of factory method pattern I found on YT. Thanks.

[@mydexcicdeja]

Excellent thank you for the clarity in your explanation and reconfirmation during the session

[@gregridd]

You are a great teacher Christopher Okhravi!

[@jagmagana]

Thanks for this design patterns series, i downloaded all videos because i cant lost this treasure...

[@JeffreyConcerto]

Great teacher! You did an excellent job breaking down the pattern, and I completely agree that the HeadFirst examples of Pizza and Pizza Stores are terribly confusing and uninspiring compared to their other examples.

[@SaurabhGuptaicecool]

Sir, you are a life savior. Thank-you.

[@itisprofile]

Very clear explanation! I haven't found any other channel or video that explains the concept like you did.

[@honey30prachi]

i just love your way of explaining difficult things. Seriously these videos are very helpful

[@mikhailmikolaichuk1974]

It looks like we have misunderstanding here. The thing which was described in the video is en.wikipedia.org/wiki/Abstract_factory_pattern Whereas Factory method pattern is literally about "method" . en.wikipedia.org/wiki/Factory_method_pattern

[@elinorkent7188]

the best tutorial for this. watched many, but now i actually understand it.

[@dark808bb8]

I think it is really interesting how you show that various types of creators and products can reduce to a few creators and products with different properties.

[@KuzyoYaroslav]

This is just awesome, I have never thought its possible to explain those patterns so interesting with just white board. Thanks for you work.

[@sastashroud7646]

dude i am indian and these video lecture on design pattern really saved my life no one has taught as well as you have thank you bro really appreciated your work

[@ChristopherOkhravi]

Thank you for the comment. I’m very glad to hear that 😊😊 Thanks for watching

[@sastashroud7646]

@@ChristopherOkhravi your lecture really helped me I attempted every question on design patterns thanks

[@hamzac.4555]

I was looking for a real tutorial about design pattern, when you said dont use static method, I subscribed and gave a like. Keep it up bro !

[@40ozhemlock]

that was a moment of clarity for me too

[@OritNeeman]

YOU ARE AWESOME!!! Thanks to you I now REALLY understand design patterns. Everything you teach is so clear and it's fun and interesting to learn from you. Thank you so much. You are the best.!!!

[@ahmedbishree9429]

I read around two different books and a few video courses but believe me I didn't understand as much as I watched your first 20 minutes many thanks.

[@nishanckarunatillake3361]

Hi, I think this is a fantastic set of tutorials. I found it really useful. Hope you will find more time and energy to progress though the book quickly and not give up.

[@ChristopherOkhravi]

Thanks for the encouragement! I'm very glad they're useful. Will try my best indeed.

[@Khatsil]

the asteroid example is really good!

[@andypye4006]

Thanks for these videos Christopher. You have a superb, enthusiastic delivery style !

[@brunon.8962]

This guy is actually better than the book itself.

[@pionapior]

Like before a watch because you are a legend !

[@ChristopherOkhravi]

:D

[@ecsweb-studio2732]

That man is amaizing he is real great actor. Holywood is mising real great actor.

[@aymansafi2998]

let hem here dude so he helps us in programming stuff :D

[@gytisdobrovolskis5933]

Goddamn the factory pattern is already quite complicated here. And now I checked on some pluralsight tutorials - and there are a lot more complications, pitfalls and ways to do it. I think I will skip this pattern for now.

[@bloomtrading]

this is the best channel ever

[@yazanal-shawaqfeh1203]

Easy way to understand why each class/interface is required: - Main factory class encapsulates all different heuristic factories and decides which heuristic to use - A heuristic factory decides which object out of a collection of objects to instantiate. Since it is not sure and requires access to all possible objects, it refers to the superclass of the objects. - The collection of objects are related/connected under a superclass, hence they are subclasses.

[@GeaForce]

Christopher: Check this book, it's really easy to understand Also Christopher: Man, the examples on the book are catastrophic

[@rsdntevl]

The game example gives good insight on the dynamic nature of the factory method!

[@ChristopherOkhravi]

+rsdntevl Cool! I'm glad to hear. Thanks for the specific feedback :) and thanks for watching :)

[@kenya6749]

This helped SOOO much before my exam tomorrow! THANKS!!

[@paull923]

by far the best videos regarding design pattern

[@tsumardi]

great explanation . I think you should give explanation in the following order in the beginning: text definition, purpose and why we need it. dig deep then summarize to some that want to skip the details. You are doing awesome job and quick refresher for me without watching it all the way to the end. Thumbs up.

[@mannyfay2524]

You explain this topic super well and I like your speed of speaking very much!! If you want to keep evolving your way to make such awesome tutorials, please avoid your huge amount of jumping because of cutting your videos.

[@miloszbacnik3366]

I must say, that I've jumped directly to GOF book. Things were blurry. But, this whole video set makes things way more clearer. So, a BIG thanks from me :)

[@wearemiddream]

i've been trying to understand this for a minute and you just nailed it dude, thank you!

[@georgebrandon9675]

Great video! Still the best explanation on the internet

[@czarlp]

You are amazing as a teacher dude, I find it very hard to not understand and follow everything you are saying, it's almost intuitive. Keep up with cutting the video in a lot of pieces, I think it makes the learning process easier if you "shoot" sentences instead of sending a big package of words. I don't know if that makes sense but anyway, keep up with whatever you do. Kudos to you.

[@random-bucket5998]

You are just awesome .. I saw all the videos on design pattern.. I understand just like a miracle happened and enlighten my mind..

[@sharathchandra5314]

I am new and i am late. But i am hypnotized and will be sticking to your rest of the videos 😀

[@Monk-wv4ub]

You are best guru for design pattern .

[@WillEhrendreich]

These are the best explanations of these theories on KZbin, I swear. Thank you so much for sharing your knowledge with us all.

[@sudeepkumaragarwal2419]

I think in the video simple factory pattern is explained in place of factory method. They have very slight different and this difference is explained very well by taking the pizza store example in the book.

[@drapala97]

i love this channel so much, Mr. Okhravi is a bless for the community. God bless you

[@sumansauda3981]

This guy is just amazing!!!!!!!!!! He has made this so simple and easy Thank u sooooo much

[@indramaniarora7901]

Best channel for design patterns. Sad there are no new videos from him

[@russiafromtheinside2776]

It worth watching not even for pattern understanding but for the plot. I was like - wow, what's going to be next with these asteroids and animals? Your expressions are just amazing. Thank you very much. Subscribed.

[@guilhermerenna]

Your videos are awesome! I have watched them all in the past, and I continuously come back to them and use them as a reference. I can't thank you enough!

[@luisfelipedasilva7128]

You´re incredible, man. The way you teach is awesome. I can´t get away from the video, i just want to watch more and more

[@naila7765]

Best explanation of design patterns I found. Thanks!!!

[@sahilkaul6199]

god bless you christopher, i could never understand why we needed this pattern. Thankyou for making it so clear :)

[@Coolharshit149]

Wow, i really felt when you said about the pizza example from the book. You cleared all the doubts

[@nipulsindwani117]

The best design pattern series.