Master the Power of Composite Pattern in Rich Domain Modeling

[@num1nex337]

Honestly, thank you so much for making those type of videos, as someone who is relatively junior it is hard to find a content that would allow me to level up. Most of the stuffs out there are 50th variation of how to use mediator or create a validation filter, but your videos are golden, they touch real world problems and provide solutions that can be extrapolated to other scenarios aswell.

[@michaelkoss]

"This is a trick question; you should not like it" 🤣

[@adiazwise]

Great content, Thanks, I'm motivated to follow you courses in Pluralsight on these topics.

[@saifeddinebenromdhane7553]

Just wanted to say Thank you, i really do appreciate the kind of content you make.

[@zoran-horvat]

Thanks!

[@SteveNgaiCheeWeng]

Hi Zoran, what is your thought on using Strategy Pattern for the above requirement?

[@zoran-horvat]

How would you apply it?

[@matthewjames1648]

My take is that the main difference will always be: Strategy Pattern will have Type A choose from Types b-n and determine which strategy should be the strategy(ies) to use. Composite Pattern will have Type A compose or aggregate the results from Types b-n in some way. So I don't believe Strategy Pattern would be a suitable drop-in replacement here in Zoran's example, unless you really misuse the Strategy Pattern.

[@ivandrofly]

Thank you :D

[@АлексейДемин-ъ5ж]

tnx for the video

[@ghevisartor6242]

Amazing video, this is so helpful as a junior. One question: 2:05 At line 35,36,37 you register some formatters, did you make a video on those too? I see you register them with the interfaces, is it just in case you have to swap the implementation or is there more going on?

[@zoran-horvat]

All those formatters implement the same interface, and so does the composite. That is the primary enabler for the Composite pattern.

[@hemant-sathe]

Excellent video. In business, the discounts or rules for discounts are configured by business people and we don't want any code change or we have a multi tenant application and can't code for every customer. In such scenario the rules get implemented as some policy or a rule set and are stored in text file. Please consider showing a small example of how to convert this same discount rules to an external, say json/xml, file and load at the start.

[@zoran-horvat]

I don't plan such a video now. I hope it was clear from the video that the object graph should be created by some object dynamically, rather than statically as I did in the demo.

[@marvinxulu7816]

why not use the factory pattern ?

[@zoran-horvat]

@@marvinxulu7816 How would that solve the problem?

[@marvinxulu7816]

@@zoran-horvat just asking as a junior these design patterns are new to me.

[@krajekdev]

@@marvinxulu7816 Factory pattern solves different problem than the one presented in the video. However, you are right, that within whole functionality a factory pattern could be used, for example, to instantiate some discount objects based on provided application configuration. In other words, factory pattern in a "creational" pattern, whereas composite i a structural pattern.

[@ghostnguyen]

Hi Zoran, I think there is a better implementation that using 'true' Composite pattern. Your code still gets machine states which would be source of bug. Do you have repo url so I can create pull request?

[@zoran-horvat]

There is no repo for this demo. What do you mean by sources of bugs, and what is your suggestion on how to fix that?

[@ghostnguyen]

@@zoran-horvat Method GetDiscountAmounts in ChainedDiscounts should and could be improved. It has state, nested loops, two if statements and also middle return statement. Suggestion: ChainedDiscounts should be a chain of discounts, not a list of discounts. More suggestion. Then you don't need a ChainedDiscounts.