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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?

#81

Post by professoretc »

mattnewport wrote: post #9
est wrote: post #3

IMHO inheritance works and only works for graphics related programming, e.g. GUI and games. Visual objects can be abstracted in the manner of inheritance.

Inheritance doesn't work well for games, that's why so many games take a component based approach like Unity, or full blown ECS.

The implementation of inheritance (more specifically, polymorphism and dynamic dispatch via vtables) is a problem in games, because it adds an extra layer of indirection, and screws with cache locality. But the semantics of inheritance (X ISA Y) still apply. In an ECS, the implementation is different (struct-of-arrays) but you can still think of an entity as "inheriting from" the various components its built from.

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

#82

Post by cess11 »

xwolfi wrote: post #50
cess11 wrote: post #26

Earlier quoted context omitted.

I disagree. Starting with separating class and object have never been helpful when I've tried to teach computer programming, while functions seems to have been more intuitive to those people. After a while you get to closures, which are pretty much objects without classes, and then factory functions that produce closures and there you have something like a class as well. If I were to design a course I'd probably foll…

But you go from the bottom up here, I don't like to describe it that way. I prefer to say that we naturally classify objects around us using fuzzy boundaries like "a house", "a cat", which don't exactly mean anything: they are templates we use later to actually generate an actual house, or an actual cat (on a piece of paper as a drawing for instance). The world being separated between our internal classes and the int…

I prefer to start with an interactive programming environment, like a REPL, to keep the feedback loop tight and code short. If I needed to talk for ten minutes about templates and instances and how you need to have a little meeting with yourself and do modeling I'd have lost their interest right away. These words mean nothing to a newbie, unless they're some kind of philosophy nerd so I can hook into ancient greek ideas about Forms or something.

'Here is a way to do simple math, here is a way to glue text to text, now that has grown a bit, you can shorten it for repetitions by giving it a name like this', and so on.

And to me, starting out functionally is easy. Data is pretty much always a given, it's very rare in practice that I first need to model speculatively and then generate data ex nihilo unless I'm creating mocks. Usually there is a data source, a file, a network API, whatever, and then I start building against that. Small, simple things at first, like mapping all the input to an output interface, then add transformations and output for these, and so on.

In general I spend more time thinking about the shape of data I already have than architecting code or inventing models.

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

#83

Post by rtz121 »

mrkeen wrote: post #73
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. 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. The runtime part is what I dislike. If I have a fruit which is an apple or a banana, I can't pass that to a method expecting an apple or banana. It can only be passed as a fruit. > And if you want to avoid huge if-else statements, you should pu…

> If I have a fruit which is an apple or a banana, I can't pass that to a method expecting an apple or banana. It can only be passed as a fruit.

You can by overriding the method on apple or banana. If your method is on some other object, then yes, you cannot do this unless your programming language supports multiple dispatch.

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

#84

Post by seanwilson »

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 world people still cling to the cascade as a best practice for some reason.

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

#86

Post by parpfish »

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…

if i were writing an intro to programming book, i would introduce OO as a means of building encapsulation. i'd only get into inheritance in later chapters.

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

#87

Post by pgwhalen »

angiosperm wrote: post #31
high_na_euv wrote: post #5

Do they? I rarely see people using it directly and I think this is fine

Most of us have no contact with Java. But Java offers little else than inheritance to use to organize a system, so Java coders use it for everything. They are not exactly wrong, except in using Java at all. But sometimes is all that is allowed.

This is much less true for modern Java than it used to be, with records, pattern matching, sealed classes, etc.

The trick though is you actually have to use modern Java, which means you need to both be on the right version of Java, and have developers that understand the value/power of these newer constructs. Which is surprisingly rare for a programmer that self-identifiers as a Java programmer.

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

#88

Post by chowells »

dboreham wrote: post #85

It's not bad. People like to feel smug by saying OO is bad and hence inheritance, meanwhile using some construct in their FP that is really the same thing.

Can you explain how any construct in FP conflates subtyping and code sharing the way OO inheritance does?

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

#89

Post by wwweston »

otikik wrote: post #54

Inheritance is a local maxima. When the hierarchy of classes to consider is small, it often “seems to fit”. It allows the programmer to progress quickly and with low effort as a lot of the code sharing behavior is provided by the inheritance mechanism. Trouble often comes down the line. We keep adding classes, and soon we find that the hierarchy no longer is “shaped like a tree”. A soccer ball is a spherical object b…

Hence traits.

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

#90

Post by Supermancho »

cryptos wrote: post #59

My impression is that inheritance is in many common programming languages the easiest way to share code. Sharing code in another way would require some more thoughts and sometimes code, so the lazy programmer takes inheritance. Traits as a general concept would be very useful in many programming languages, but only some (like Scala) have proper support for it. In principle a Java interface with default methods (imple…

Traits are increasingly common.

https://en.wikipedia.org/wiki/Trait_(computer_programming)

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