Proxy Pattern - Design Patterns (ep 10)
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- Опубліковано 31 тра 2024
- Video series on Design Patterns for Object Oriented Languages. This time we look at the Proxy Pattern.
► The playlist
• Design Patterns in Obj...
► Head First: Design Patterns
geni.us/nlbA6
► Design Patterns: Elements of Reusable Object-Oriented Software
geni.us/PsXmo
► Premature optimization
en.wikipedia.org/wiki/Program...
citeseerx.ist.psu.edu/viewdoc/...
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The community is missing someone like you.
2023 and we still enjoy such 37 min in a row.
Dude I really like how you repeat every one of your definitons at least twice... The first time to hear it and the second time to rethink it! You are a great teacher!
"Instead of calling the THING you want to call
you call the THING which call the THING you want !!" Nice definition, liked it!
Hehehehe 😁😁
It really was someTHING! 😂
00:01 The proxy pattern provides a surrogate or placeholder for another object to control access to it.
01:56 Proxy pattern is used to control access to resources and solve access-related problems.
06:01 Proxy pattern adds additional behavior to control access to the underlying object.
07:58 Using a virtual proxy allows for additional behavior before making calls to an object.
12:12 Using methods is a flexible approach that allows for future changes.
14:13 Premature optimization can lead to inefficient code
17:59 Proxy pattern allows deferring the instantiation of the underlying book parser
19:42 Proxy pattern is used to create expensive objects on demand rather than immediately.
23:23 Proxy pattern is used to control access to an expensive operation.
25:11 The proxy pattern controls access to the real subject and follows the same interface.
28:44 The proxy pattern involves a proxy class that acts as a placeholder for another class, known as the real subject.
30:17 Create an instance variable that defaults to null for Lazy Book Parser Proxy.
33:58 The proxy pattern delays the instantiation of a concrete book parser until it is needed.
35:44 The proxy pattern allows instantiation of the book parser only when required, improving performance.
Great video, but can you move ur camera slightly to the right next time so i can see the cat better? :P
I cant see a thing
Bruh!!, I watched this before my final and you made it super easy to understand. Hours of reading on this pattern were pointless. Crystal clear explanation. Keep it up and two thumbs up!
I was completely lost, and i had to understand and learn design patterns.
i found this channel, and now i get it all.
thanks for your time and effort Chris.
My mood rises when I see new episode. Thanks a lot MAN!
Thank you very much. That makes me happy to hear. I wish I could deliver more and faster. Gotta keep the balance with my day job :) But as I get the flow up I will hopefully be able to. Thank you very much for watching :)
I really like the effort you give while explaining the concept. you are very good teacher. Hard to find teacher like you
This is by far the best explanation of the proxy pattern I've watched on youtube! Thank you!
You are an effective and succinct communicator. You make learning infectious. Are you a professor or desiring to be?
As online learning continues to become an educational alternative, and given the increasing university tuitions, online instructors like you are becoming a threat to the educational status quo.
You have a gift and I believe it will take you very far in your career.
EXCELSIOR!
i've seen he is a proffessor for 8 years now ;)
I love your explanation that patterns have different intent even if implementation strategies match sometimes.
Great Job!! I have never seen any video that explains design patterns so clearly. Thank You for making my life easier to understand Design Patterns.
I'm reading the Head first design patterns book, I used to think that I already had a good understanding of OOP, but that book changed everything, I realized I just knew the name of the tools and maybe how they were written in java, but I had no idea how to use them, after learning about design patterns marked a new start for me.
I came here to have some help with the Proxy pattern and you were awesome, thank you, now I'll go ahead and start reading the chapter about the proxy pattern in the book, keep it up man, you are a great teacher.
Bringing up the "Premature optimization" is brilliant 💡. Thanks!
Hey
Christopher, thanks for sharing these knowledge so generously, hope everything's well with you.
Hey Christopher, Thank you very much for making these videos. I know they’re a lot of work. You teach the way I think. If that makes sense. Brilliant job!!!
maan, I've been watching these videos and writing notes all day long. Thanks.
The best Design Pattern playlist on UA-cam! Your explanation skills are very powerful...listening to you is funny and not boring! Thanks to you I'm gonna pass my exam on Design Pattern!
I just don't understand how do you manage to make it so simple... Thanks alot for this wonderful explanation... 😀
Man, your examples, just make it so easy, it was a nightmares before i know this playlist, thank you
Hi, I am a student from Taiwan, I really like your explanation, really help me a lot! Thanks!
open, smash 'like' button, watch - my algorithm for your videos. I call this pattern "gratitude". Thanks a lot for your great job!
The one reason I keep coming here is that he keeps repeating what he is teaching. That really helps to understand the topic better. Great contents!
Thanks Christopher for you detailed view on patterns.. I really find them very informative and like the simple way you have explained these topics. Keep the good work .. Way to go.. :)
Man I love your videos. You make things that were unclear to me looks like really super easy.
We need more people like you! Everything I search on UA-cam for Object-oriented programming is either trival or just not helpful. Thanks to you I understood the patterns I needed to understand for my exam. Thanks!
They could be a little shorter tho :D
As usual amazing explanation Chris. Keep up the good work. Thanks a lot.
+pradeepsanju Glad to hear! I will. Thank you for the encouragement and thank you for watching :)
I am really upset i did not find your tutorials all these years on UA-cam when ever i searched for "design patterns with Java". But better late than never. Thanks dude.
Learnt first 10 design patterns and done for now. Will come back later, maybe during the 2nd half of 2020.
Excellent explanation! Thank you so much!
I love your work. Thanks a lot. Please continue this series
I had astigmatism and I started wearing new glasses. I was happy to see everything clear. Until I watched this video: D.Even so thanks for your informative video :)
These videos are amazing. You should create a design pattern playlist for easier consumption
It would have been pretty cool if you had talked a little bit about how virtual proxies can also override a client's method or property. This, in my opinion, makes virtual proxies super powerful (assuming, of course, that the language allows for it and that the client class has been defined appropriately) Thanks a lot for the great video!
Chris, you're an awesome pedagogue !!! Thanks a lot !
quite interesting and explain in an abstract way. which make it more interesting. appreciated your efforts keep it up buddy..
I completely lost track after that cute student walked into the class. :D
114 likes, 0 dislike ... I'm really NOT surprise .. your explanations are perfect
Perfectly explained, thank you!
Thank you Chris, for amazing tutorials. Isn't this pattern very similar to singleton pattern, except that we create object on-demand through some method instead of constructor in singleton, or am I understanding this wrong?
Instead of book I prefer to watch this playlist again xD
Thanks for such a brilliant series on the design patterns.
Would like to know more about improving application performance from developer's perspective, but in "Christopher Okhravian" style.
I really like your videos. Thanks a lot !!! They are really helpful!
You are a great teacher .....Love from India .
Thanks Christopher Great Explanation
Your videos are fantastic and informative!
you really helped me during my exams. thanks bro
Great video. Content and explanation were really useful, thanks! I know you mentioned the autofocus and are aware of it but just a suggestion: Perhaps avoid using autofocus all together? Use a deeper depth of field and set your focal point to 2/3rds of the distance from the whiteboard. After this is set, leave the focus for the entire video. There's no need for the camera to be constantly re-adjusting focus as you move your arm back and forth because that data is irrelevant to what the viewers need to see.
Thank you, these videos are super informative!
Your content is really good tho.
I can't wait to see what more interesting things you're going to bring to the channel!
Im glad to hear :) and glad to have you onboard :)
Awesome as always, you are a very good teacher! Just a question: what about the GoF patterns which the book "Head first" doesn't explain? Are you going to make some videos about them? I hope so, it would be great :D
Very well explained. we love your lectures and your cat.
Haha thanks! I'm glad to hear :) Actually there are two cats but one of them seems to always be around when the camera is out :D Thanks for watching :)
Again nice explanation. Thank you for share your knowledge :)
A huge thanks to what your doing here. Bought the book and watching all your videos..
I get the proxy stuff and see the benefits. I am wondering about the caching. Do you have material/reference as to generically choose a caching methods? Being mostly PHP oriented I wonder about the duration of the url request cycle and I am fighting with this concept.
Really like this playlist. A bit late to the convo but in the example in the vid, in the case we're doing this because we're using an external lib, then how can we inject a proxy after the fact? Surely if it wasn't designed with the interface, we can't make the concrete subject, i.e. BP in the example, implement a new interface later. Correct?
Christopher Okhravi, create more content. You explain very well and in depth !!
Question: is it still appropriate to use proxy pattern when you own the original object implementation? It makes sense to proxy another library object to enhance or change it’s behavior. But does it make sense to proxy your own object that you could just modify instead of proxying? I know of the open-close principals. So proxying already existing object that I own the implementation of would obey the open-close principle but also would possibly create layers upon layers upon layers. Also, I’d like to hear more on dangers and gotchas of each pattern.
Thanks a lot! Christopher, it is the greate explanation, which I ever heart!
awesome example . thanks alot!
you are AWSOME keep up the good work, it helped me so much. thank you
great video. Guess, who uses the proxy pattern heavily as you've said for the lazy initialization? of course, hibernate. When you declare explicitly that I'd like to have an object lazily initialized, hibernate obliges it by using proxy around it. So that ORM class is instantiated only when we 'really' want to do something on it, until then it is just hanging around there as a simple proxy class . Again, great video!
Hi Christopher,
I must firstly say that you’re a great teacher. I’ve been feasting on your presentations on Design Patterns and enjoying every bit of it.
I’ve looked at this particular tutorial 3 times but I couldn’t seem to grasp the concept properly then I found why: I think your example don’t quite fit the pattern. Here’s why:
The base interface on the right, ie the Implementor needs to itself be a specialised form of the Abstraction hence the name Implementor. With this understanding the definition makes total sense “Decouple an abstraction from its implementation so that the two can vary independently”.
In your example IResource would need to be a specialised version of View to fit the Bridge Pattern which makes no sense.
My comment is not to take away from your work by the way, your work is awesome stuff.
Let me know what you think.
This is a really powerful pattern.
brilliant mate, keep up the good work
Great videos and explanations! Thank you very much. I was looking for an episode on the differences between facade, proxy and decorator patterns but couldn't find it. Maybe you'd be so kind to point to it. Thanks! P.S. Love it when your cat participates :)
I think what you mentioned around 11-12 minute is "encapsulation" , where you can access the field through method instead, by using setter and getter method. cmiiw
Sorry for my misunderstanding but the `return this.parser.getNumPages();` should happen outside of the `IF` block, right?
You very good explanation. I like it so much!
Thanks! And thanks for watching :)
Cool! This is the first video I saw from you, but I immediately subscribed.
Awesome. I’m glad to hear :) Welcome :)
Thanks a lot for this amazing explanation 🤓
Nice explanation Christopher !
+Amann Thank you. I'm glad to hear it's useful. And thank you for watching :)
Great video as always! small criticism: I think a better example would be to introduce a "setBookString" method instead of working with constructors. Since the constructor is not part of the IBookParser interface, we can not really rely on it when Proxying the BookParser class.
Can't you give the String book (as an argument) directly to the method instead of making it a field variable of the BookParser? or is this part of the pattern?
Great video. Very informative.
Group of Devs said design patterns are difficult till Christopher enters the room.
Thanks for the easy-to-understand explanation & cat though 😀
great work. Thanks for the video.
One question, At 24:10 proxy Object has-a concrete real subject. What difference would it make if we use ISubject interface in place real subject inside the proxy Object ?
Thanks very much for these videos and I love your cat! :)
Hey Christopher ,
Thank you very much for this great video series .
According to the code that you have mentioned at last it seems same to singleton pattern.(one time creation object) Can you please brief me how this proxy pattern is difference from singleton pattern ??
great! Thank you!
Amazing video, thank you very much
A Very very good explainer
Great Video!!
Can we use a singleton for this example since we are only instantiating the Book Parser once, upon the request of a method?
Good explanation MAN , thank you
Hello Christopher, I like your videos and the way you explain it...I have been following your videos for my better understanding abt DP....Can I request you about including real business scenario where we can implement these DP's...Please have a 10 min of slot in your video abt telling us real scenarios where we can implement this DP....
Best examples of Proxy pattern are Mockery(mocked objects or services) as used in unit testing.
Your explanation of concepts and examples are easy to understand! I even treat it as a kind of relaxation!
Though I fell asleep for times in this episode (maybe just because I watched it after dinner...), I found I was still keeping up with the pace of the video :)
Thank you so much!
Hah! :D :D :D
Awesome content, thanks
Someone would say ANOTHER ONE! Great Job Dude!
+konzinov maverick Yeeeeeeea they don't wanna see us win!
Hi, I can not be able to find a video where you have captured about the differences between proxy, adapter, facade and decorator patterns ?
can you please point me to that video? so that i can continue with that.
Amazing explanation 😍 i love you
Christopher, thanks a lot, very nice explanation :)
And thank *you* for watching :)
8:04 NOOOOOOOOOOOOOOOOOOOOOOOOOO ! I did not have time to take notes !!!! 😱😱😱😱😱😱😱
No seriously this is good and I have OneNote opened to keep the important bits.
About autofocus I'd say in the context in which you shoot, you'd probably better find a manual setting that works. Autofocus is dynamic and can misinterpret the subject at times. With a long enough depth of field you could not need to change anything at all and be sure the image is neat for the desired scene setup.
The smaller the aperture the longer the depth of field but also the less light = greater likelihood to need external light.
thanks a ton for this amazing video.................
When should I start learning design patterns? Pls tell me I'm in 1st year of college and I've learned till template class
Is there a video about the difference between the proxy and the adaptor as you said? I mean their nuances?
Nice Explanation Christopher, thank you for the Video. Just got a thought here instead of making book name as member variable can we pass it to the method getNumberOfPages(String bookName)? As the real object BookParser is independent of the book and tying it to a book name in proxy at instance level we have to set the new name always in the proxy book parser?
For eg something like below:
public class LazyBookParserProxy {
private BookParser bookParser = null;
public getNumberOfPages(String bookName){
if(bookParser == null){
bookParser = new BookParser();
}
return bookParser.getNumberOfPages(bookName);
}
}
What say? and does the proxy object LazyBookParserProxy somewhat ring bells of singleton pattern in this scenario? :-)
Again another great video thanks.
Is it a good idea to combine a Proxy and Singleton pattern then? A single accessor to our resources ?
Congratulations and thaks to share!