Inheritance starts to suck > 1 level deep.
Multiple inheritance starts to suck at the point people discuss adding it to a language, or a few femtoseconds after the big bang, whichever comes first.
You will still have private/public sections, interfaces (unless you class them as inheritance), classes and instances, the SOLID principles, composition over inheritance. OOP is a lot more than just large family trees of inheritance, a way of thinking that's been moved away from for a long time.
Yep. I'm old, cranky, and prone to broad statements to get reactions.
That said, for any of you all that love inheritance, I'm judging you so hard. So hard. Very judged. I probably hate your code, and your friends' code, and your last teacher's code. Especially your last teacher's code.
Anyone who praises FP is either a student, works primarily in academia, or otherwise never had to look at a deep stack trace in their life.
Every time a production system spits out a backtrace that's just 15 event loop calls into a random callback, I lose 6 months life expectancy. Then I go look at the source, and the "go to definition" of my LSP never works because WHY WOULD IT, IT'S ALL FUNCTIONAL hapi.register CALLS
I hate it I hate it I hate it I hate it. I support UBI because the people pushing functional programming in real production systems should be reassigned to gardening duties.
I have the same problem with oop. 10 levels of encapsulated calls just to see you were in an overridden methods without enough data to find out which implementation it was. Ugh
The venerable master Qc Na was walking with his student, Anton. Hoping to prompt the master into a discussion, Anton said "Master, I have heard that objects are a very good thing - is this true?" Qc Na looked pityingly at his student and replied, "Foolish pupil - objects are merely a poor man's closures."
Chastised, Anton took his leave from his master and returned to his cell, intent on studying closures. He carefully read the entire "Lambda: The Ultimate..." series of papers and its cousins, and implemented a small Scheme interpreter with a closure-based object system. He learned much, and looked forward to informing his master of his progress.
On his next walk with Qc Na, Anton attempted to impress his master by saying "Master, I have diligently studied the matter, and now understand that objects are truly a poor man's closures." Qc Na responded by hitting Anton with his stick, saying "When will you learn? Closures are a poor man's object." At that moment, Anton became enlightened.
Can someone please enlighten me on what makes inheritance, polymorphism, an operator overloading so bad? I use the all regularly, and have yet to experience the foot cannons I have heard so much about.
I don't think that the anti-oop collective is attacking polymorphism or overloading - both are important in functional programming. And let's add encapsulation and implementation hiding to this list.
The argument is that OOP makes the wrong abstractions. Inheritance (as OOP models it) is quite rare on business entities. The other major example cited is that an algorithm written in the OOP style ends up distributing its code across the different classes, and therefore
It is difficult to understand: the developer has to open two, three or more different classes to view the whole algorithm
It is inefficient: because the algorithm is distributed over many classes and instances, as the algorithm runs, there are a lot of unnecessary calls (eg one method on one instance has to iterate over many instances of its children, and each child has to iterate over its children) and data has to pass through these function calls.
Instead of this, the functional programmer says, you should write the algorithm as a function (or several functions) in one place, so it's the function that walks the object structure. The navigation is done using tools like apply or map rather than a loop in a method on the parent instance.
A key insight in this approach is that the way an algorithm walks the data structure is the responsibility of the algorithm rather than a responsibility that is shared across many classes and subclasses.
In general, I think this is a valid point - when you are writing algorithms over the whole dataset. OOP does have some counterpoints encapsulating behaviour on just that object for example validating the object's private members, or data processing for that object and its immediate children or peers.
If the only tool you have is a hammer, everything looks like a nail.
That's the only thing I can think to answer your question. There are some problems that are best solved with other tools, like text parsing for example you might want to call out to some code written in a functional language.
I don't really think it's any of those things in particular. I think the problem is there are quite a few programmers who use OOP, especially in Java circles, who think they're writing good code because they can name all the design patterns they're using. It turns out patterns like Factory, Model View Controller, Dependency Injection etc., are actually really niche, rarely useful, and generally overcomplicate an application, but there is a subset of programmers who shoehorn them everywhere. I'd expect the same would be said about functional programming if it were the dominant paradigm, but barely anyone writes large applications in functional languages and thus sane programmers don't usually come in contact with design pattern fetishists in that space.
Operator overloading is adding complexity, making code subtly harder to read.
The most important lesson for code is: It should primarily be written to be easy to read by humans because if code is not trash, it will be read way more often than written.
Because an object is good at representing a noun, not a verb, and when expressing logical flows and concepts, despite what Java will tell you, not everything is in fact, a noun.
I.e. in OOP languages that do not support functional programming as first class (like Java), you end up with a ton of overhead and unnecessary complications and objects named like generatorFactoryServiceCreatorFactory because the language forces you to creat a noun (object) to take an action rather than just create a verb (function) and pass that around.
I think the main problem is that people try to shoehorn OOP mechanics into everything, leading to code that is hard to understand.
Not to mention that this is basically encouraged by companies as well, to look "futuristic".
A great example of this approach going horribly wrong is FizzBuzz Enterprise Edition.
OOP can be great to abstract complex concepts into a more human readable format, especially when it comes to states.
But overall it should be used rarely, as it creates a giant code overhead, and only as far as actually needed.
Oh no, the FizzBuzz EE has evolved since I've last viewed it! 😱 Is it bad if it actually reminds me of my current work project's backend (that I haven't written) a bit?
I got as far as seeing they chose Java and opening the constants file, and immediately executed a strategic withdrawal. I love that people went to this level of detail
People (sometimes) use it far too much and in wrong ways.
Like inherit when you could just instantiate, or use a template.
Or when "everything should be a class" was also a bummer (inhetit "run()"), like I'd instantiate "main" twice (cool if it had worked I guess).
Or old code written by "wizards" where they cast cast cast instances onto other classes to use specific behaviour in crazily dangerous manners. And you're the one to "fix it" because it doesn't work well...
Just like any software design principle, it's understood at a surface level by tons of bad developers who then try and solve every problem with that one principle. Then slightly better developers come along and say "ugh this is gross, OOP is bad!" And then they avoid the principle at all costs and tell everyone how bad it is at every opportunity.
Inheritance makes complicated objects that would otherwise be impossible possible, but it only works if you know those objects really well. The problem is people write ridiculously complicated mystery objects in libraries and no one knows what's going on anymore.
Springboot is very confusing. The inheritance tree is insane, they created a class for everything, which I get.... But it is so hard to understand the whole scope their design.
Those are nice. Services that manage data are an example. Having the class also declare how to interact with the data is nice.
My most OOP pattern I like using is implementing an interface with an abstract class for "standard" implementation. Then implement abstract methods for a concrete thing.
Excuse me if I don't appreciate when the compiler adamantly refuses to do its job when there's one single unused variable in the code, when it could simply ignore that variable and warn me instead.
I also don't enjoy having to format datetime using what's probably the most reinventing-the-wheel-y and most weirdly US-centric formatting schemes I have ever seen any programming language build into itself.
I used to think I was just a fanboy. But as time went on and I gained more and more experiences, I've only become all the more sure that ANSI C is the only language I ever want to write anything in.
I like polymorphism. Having to have a hundred differently named functions or structs or something that do the same thing but slightly differently in Rust is annoying as hell. Especially with all the underscores you have to type... If Rust were more functional though it'd make that problem go away pretty quickly.
Common Lisp isn't a functional programming language. Guile being based on Scheme is closer, but I'd still argue that opting into OOP is diverging from the essence of FP.