C++ Tutorial: the factory design pattern

Here's a simple example and explanation of the Factory design pattern using C++.
In class-based programming, the factory method pattern is a creational pattern that uses factory methods to deal with the problem of creating objects without having to specify the exact class of the object that will be created.
In this video, you'll learn how to implement one.
// Download the code here:
www.dropbox.co...
// Check out my software design patterns playlist:
• Software Design Patterns
// Check out my complete C++ videos playlist:
www.youtube.co....
// Consider supporting this channel in multiple ways:
Super Thanks
ko-fi.com/prof...
paypal.me/hank...
/ @professorhankstalica
Bitcoin: 177wfkQwzXiC8o2whQMVpSyuWUs95krKYB
Dogecoin: DRK2HDp3ZkkbFpvGZnVgMVosnBhPv8r3uP
#C++ #programming #tutorial

[@danielbruneau2936]

Thanks! Great explanation!

[@ProfessorHankStalica]

Hey, Daniel. Thanks for the beer, and glad you found it helpful!

[@alexplaytop]

Simply about hard stuff as for me, thank you very much!

[@ProfessorHankStalica]

You can do it!

[@chandusrinivas7813]

Super explanation sir, Thank you!

[@ProfessorHankStalica]

Glad you liked it

[@veronikabykova5494]

Amazing video, thank you so much! This helped me prep for my C++ code design interview:)

[@ProfessorHankStalica]

Oh, that's fantastic! I hope you get the job. Good luck! If you get it, you owe me a beer! 🍻😆

[@iaroslavz2644]

Thank you very much. It's a great explanation.

[@ProfessorHankStalica]

Glad it was helpful!

[@Muralikrishna-yz7jl]

Nicely explained.. Thank you very much

[@bartlx]

You showed a clean example of what a factory implementation 'looks like' in code, but I feel you came a bit short of 'why' you would want the overhead of a factory if you could instead create geometry objects directly based of a common shape interface. I guess you gave a hint at 13:32, making me think this is only useful when factory code and client code are written by different parties, and as a client you want a future proof way to create 3rd party defined shapes...

[@anjan8614]

Perfect sir. Thank you from INDIA. Subscribed to your channel.

[@ProfessorHankStalica]

Namaste!!

[@propov1802]

Excellent explanation.

[@ProfessorHankStalica]

Glad you think so!

[@sallaklamhayyen9876]

clear + simple = thank you so much

[@ProfessorHankStalica]

Glad it helped!

[@raht9578]

thank you so much

[@ProfessorHankStalica]

You are welcome so much.

[@RamvilasGurjar-g2o]

Hi Stalica, does the base class need virtual constructor in this method if there are other data also in the derived classes (Triangle, circle and square) ?

[@ProfessorHankStalica]

None of the classes need a virtual constructor.

[@रामविलासगुर्जर-च9ङ]

​@@ProfessorHankStalica sorry I was asking for virtual destructor

[@ProfessorHankStalica]

Never a bad idea to make destructors virtual so that way you guarantee the right destructor is executed for the right object if there is any chance for a class to be inherited from.

[@TN-cx4qi]

Shouldn’t the for loops be (Shape& s : shapes) not (Shape*& s : shapes)?

[@VoidloniXaarii]

Thank you

[@ProfessorHankStalica]

You're welcome

[@windowsbuilderthegreat3121]

Can this design pattern work for objects created on the stack rather than on the heap

[@ProfessorHankStalica]

You could allocate the Factory object on the stack and use statically allocated memory to allocate instances of each object as attributes of the Factory. Then you could return any of them on demand. Something like that might work, but would be unusual.

[@alexfu1734]

Why not using template instead of enum? Is factory required to support RTTI?

[@ProfessorHankStalica]

Just because. There's many ways you could implement a factory pattern. This is one.

[@arthurtasca4527]

nice and clear video. which advantage do you see in using a Factory class instead of a create(type t) method directly (i.e. a factory method)?

[@ProfessorHankStalica]

If I understand the question, it's a matter of encapsulation and/or closely adhering to the object-oriented programming paradigm. Of course, rules can be broken, but it's going to depend on the requirements of your project and the overall resulting design you come up with. I prefer a consistent design, so if I'm going to do OOP, I'm going to do it all the way.

[@Danta1ion]

Can I simply think that the create() method is similar to the getClass() in Java, which in C++ returns a 'this' pointer?