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If Inheritance is so bad, why does everyone use it?

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Re: If Inheritance is so bad, why does everyone use it?

#141

Post by jonnycomputer »

pdpi wrote: post #119
jillesvangurp wrote: post #30

Kotlin has a few nice patterns here. It allows inheritance but only if you mark your class as open (it's closed by default). This prevents people inheriting from things that weren't designed from that. It also has extension functions, which allows you to add functions and properties to types without having to inherit from them. This is very nice for fixing things that come with Java libraries to be a bit more Kotlin…

One of the ways that I think Kotlin and Rust are objectively better than Java and C++ is in that they have saner defaults than their predecessors (like open/final and mut/const). I've lost count of how many talks I've watched by Kate Gregory where she advocates for people tagging everything they can as const in their C++, but asking people to eat their veggies never works.

Sane defaults are the bomb. Defused bomb.

Re: If Inheritance is so bad, why does everyone use it?

#142

Post by layer8 »

VirusNewbie wrote: post #125
captainmuon wrote: post #39

I feel people don't understand what inheritance and (object orientation in general) is useful for, misuse it, and then it gets a bad reputation. It's not about making nice hierarchies of Cars, Fruits, and Ovals. For me the main point is (runtime) polymorphism. E.g. you have a function that takes a general type, and you can pass multiple specific types and it will do the right thing. And if you want to avoid huge if-e…

>For me the main point is (runtime) polymorphism. But you don't actually care about runtime polymorphism here. You care about polymorphic behavior, which can be implemented in a much more composable way with parametric polymorphism.

You can’t build a dynamic list of objects implementing the same interface in different ways with parametric polymorphism.

As another example, the Unix file interface (open(), read(), write(), flush(), close()) etc. is an example of runtime polymorphism, where the file descriptors identify objects with different implementations (depending on whether it’s a regular file, a directory, a pipe, a symbolic link, a device, and so on).

All operating systems and many libraries tend to follow this pattern: You can create objects to which you receive a handle, and then you perform various operations on the objects by passing the respective handle to the respective operation, and under the hood different objects will map to different implementations of the operation.

Re: If Inheritance is so bad, why does everyone use it?

#143

Post by constantcrying »

bartvk wrote: post #130
constantcrying wrote: post #103

I think it is pretty clear that the reason inheritance is so prevalent is because it is a superficially good sounding idea, which again and again is being put in front of people. I am sure that many, many people have had the experience of a professor tell them a nice sounding story about purely hierarchical data and went on thinking that this is the way data should be modeled. Thankfully I believe that nowadays many…

I don't know about other colleges, but when I teach my students inheritance, I tell them right away that it's a pretty bad idea. And that they will learn better ways in the next semester.

I can't speak for what has happened since I left university, but when I was a student there you got to here about cars, who are also vehicles, dogs, who are also animals and similar stuff. Which has "limited" applicability of how inheritance works in real software systems.

Re: If Inheritance is so bad, why does everyone use it?

#144

Post by krapht »

sameoldtune wrote: post #106
captainmuon wrote: post #39

I feel people don't understand what inheritance and (object orientation in general) is useful for, misuse it, and then it gets a bad reputation. It's not about making nice hierarchies of Cars, Fruits, and Ovals. For me the main point is (runtime) polymorphism. E.g. you have a function that takes a general type, and you can pass multiple specific types and it will do the right thing. And if you want to avoid huge if-e…

You’re describing the strategy pattern, which is probably one of the most practical coding design patterns. Ex: each chess AI difficulty gets its own class, which all extend a common interface.

I still find it funny that somehow the idea of runtime function dispatch via function pointer is called the "strategy" pattern.

Re: If Inheritance is so bad, why does everyone use it?

#145

Post by ben7799 »

vram22 wrote: post #121
ben7799 wrote: post #107

I love the way people take their narrow range of experience and over generalize it to everything. Bonus points for having a blog or maybe a patreon to tell everyone how it really is. We have a million flavors of the month but in the end it doesn't really matter. Pick a flavor and there will be teams that are successful and teams that are not. No silver bullet will make the non-successful teams magically turn into suc…

Ha ha, yes, happens all the time. In this case, published in a book 30 years ago, at least: https://news.ycombinator.com/item?id=40005520

Pretty sure it was in Effective Java and Design Patterns in Java 20+ years ago as well since Java is the language that gets picked on so frequently for this stuff.

Re: If Inheritance is so bad, why does everyone use it?

#146

Post by layer8 »

EPWN3D wrote: post #80

It seems like protocols solve 90% of the problems that inheritance does, but with 10% of the headaches. Instead of trying to ensure that two types can both be passed to a function that only knows about the parent type, just have a parameter that says "Whatever's passed has to conform to this, I don't care what it is otherwise."

“Protocols” is Apple-specific (or Objective-C/Swift-specific) terminology. They correspond to types 1 and 2 of inheritance that TFA mentions.

Re: If Inheritance is so bad, why does everyone use it?

#147

Post by ruszki »

ben7799 wrote: post #107

I love the way people take their narrow range of experience and over generalize it to everything. Bonus points for having a blog or maybe a patreon to tell everyone how it really is. We have a million flavors of the month but in the end it doesn't really matter. Pick a flavor and there will be teams that are successful and teams that are not. No silver bullet will make the non-successful teams magically turn into suc…

> "I/We failed with " never generalizes to "" is bad.

I thought the same for decades, then I met Groovy and Grails. Of course, it’s not bad in an absolute sense (IMHO that doesn’t make any sense), but when some problem can be found only at runtime, when any proper compiler would catch that compile time, it’s hard to argue that it’s a good direction. Especially when TypeScript made it quite obvious what’s possible only with simple type checking.

Re: If Inheritance is so bad, why does everyone use it?

#148

Post by seanwilson »

danShumway wrote: post #110
seanwilson wrote: post #84

Nobody calls it this, but cascading styles in CSS is just like inheritance and I think should be avoided for all the same reasons. I feel it's a big part of why CSS at scale becomes unmaintainable. There isn't even a built-in way to compose two classes together if you want to avoid cascading/inheritance. It looks like composition over inheritance has caught on as the better default in other languages, but in the CSS…

I'm inclined to semi-agree with this, although I'm not sure I'd be quite as adamant about it myself. But I do generally think that CSS is taught in a way that encourages some bad practice around cascade/inheritance. I will point out though that (at least in my experience), BEM solved the majority of these problems for me even without a preprocessor. The language is definitely oriented towards inheritance/cascade, but…

> But I do generally think that CSS is taught in a way that encourages some bad practice around cascade/inheritance. I will point out though that (at least in my experience), BEM solved the majority of these problems for me even without a preprocessor.

I think cascading is just a bad default, and I think methodologies like BEM agrees with this by teaching you ways to write CSS in ways that stops cascading from getting in the way.

Cascading styles are fine for styling how basic document content is shown (e.g. h2, p, a, li etc. tags) but outside of this, you generally don't want the styles of parent elements leaking into the styles of child elements. Cascading/inheritance styles is a useful tool to have, but not as the default.

I'm not saying Tailwind is perfect, but it's closer to "prefer composition over inheritance", where you can sprinkle in some cascading/inheritance where it makes sense.

Re: If Inheritance is so bad, why does everyone use it?

#149

Post by ben7799 »

ldjkfkdsjnv wrote: post #131
d_burfoot wrote: post #122

It seems like there's a huge industry of people critiquing Java and OOP but misdiagnosing the problems as technical rather than sociological. The immense pain and suffering that is related to Java and its ecosystem is because of the terrible organizational conditions that tend to co-occur with usage of Java. Big slow companies, long boring meetings, arguments about design patterns, "architects" who haven't written co…

Java complexity is also an artifact of Java being used in large complex systems. People are really complaining about how hard programming is. There are many types of large scale systems where I would only code it using the JVM, everything else is a nightmare. Big tech companies largely feel the same

So many of these articles are written by people with no CS background who then had a couple stints short stints programming and then overnight pivoted to being expert consultants. They don't really have experience building or maintaining large complex systems. I am really curious who hires them. Most of them will have significantly less experience than the senior members of a successful team, and often less relevant education.

Re: If Inheritance is so bad, why does everyone use it?

#150

Post by turnsout »

I stopped using inheritance when Swift protocols and TypeScript interfaces came along. Although it sometimes means you need to do nasty things with generics, it beats the fragility of inheritance. With ObjC, I eventually came to hate updating superclasses, because I knew it would lead to unexpected behavior in subclasses.
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