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Comment by jaabe | Hacker News Reader

I was struck by the lack of inheritance in go, that to me is brilliant.

I’ve worked with C# for a decade, and I’ve yet to see a use of inheritance that wouldn’t have been easier to maintain in the long run without using inheritance. We’ve limited our own useage to override methods in the standard library, but even then it’s often used to implement things that are really just terrible practices. Like adding search functions for AD extension fields or increasing the timeout in one of the older web clients.

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Embedding does seem like one of the decisions Go got very right.

Many languages (thinking c#, Java, c++) say they promote composition over inheritance but yet make inheritance so mmuch easier to use.

Until 1.8 Java’s composition over inheritance story was weak. 1.8 introduced default functions on interfaces, which finally allows shared functionality without inheritance. In some senses Java’s patterns in this area have been reset, and many old code bases need to catch up (and probably never will).

Well, from where I sit, interfaces are another kind of inheritance - inheritance of API rather than implementation. But once you can have default functions, that to me looks exactly like inheritance of a base class, except that the base is called "interface" instead of "class".

Am I missing something?

It's a difference of inheriting data vs. functionality, so yes, the API is what's being inherited.

Looking at the history of inheritence a few languages I know:

- C++: multiple inheritance super confusing expressions and understanding of things like diamond inheritance. Initialization becoming a really complex thing to understand.

- Java: learning from the mistake of C++, determines multiple inheritance is bad, only allows inheriting data from one super class and then API (and now in 1.8 functionality) from any number of interfaces.

- Rust: realizes inheritance of any data is bad, and only allows for any number of Trait's (interfaces) to be implemented on types.

There's a difference, and ultimately it's that you're not carrying data via the inheritance chain, only functions. The benefit here being that it's much easier to reason about a type and what data it has that determines how it works in the broader system. This allows for very explicit inclusion of data from other types, as opposed to implicit inclusion with C++ and/or Java. In the end moving away from data inheritance leads to fewer mistakes and easier understanding of the code.

Q: Who uses inheritance in C++, anymore?

A: Java coders.

Inheritance defines a mechanism that is sometimes useful. It is useless as an interface design tool.

With Java 1.8 you can ask the same thing about Java and the answer would be the same.

I didn’t mean to suggest that it’s idiomatic in C++ to create strange inheritance graphs, anyone who’s done it once realizes it’s a bad pattern. The issue is more that the language -allows- it.

Except that a class can inherit from multiple interfaces.

Composition over inheritance solves only certain language problems where limitations of expressive power make the code less transparent or flexible, but it’s not a solution for decomposition. The problems with properly used inheritance arise only in sufficiently old and evolved code, because decomposition of one domain does not necessarily describe well another (evolved) domain. Programmers tend to think that every problem in the world should be addressed by better coding, so they try to change their coding practices. In fact, solution here is managerial - throw away the old code and do the decomposition once again, for the new circumstances and new requirements. OOD and inheritance work well, so let’s not blame them for the use cases which they cannot solve.

100% this. We're never going to built a perfect sand castle.

IMHO - There are many managerial short comings in software development that lead to abuse of legacy design. OOP by design allows you to abstract and ignore not only original implementation decisions but reflections of those decisions in the architecture. Polymorphism makes sense when it's the classic ICat: IAnimal example but so often it _becomes_ IHouseFly : IAnimal because all the contracts expect IAnimal and the deadline is.....tomorrow.

I personally don't have a good solution given the pragmatic counter argument that the ROI on a system which is cheap to develop but is patched over 5 years may be equal to or cheaper than one that is expensive to develop and _still_ needs to be patched over it's 5 year lifetime. Let's call this the used car problem. A new car is more reliable but now that used cars are reliable _enough_ it's harder to convince people _not_ to gamble with a lower upfront cost.

I absolutely _love_ Rust and the code I'm written feels bullet proof. No idea how long it would take a team of my C# peers to be even 1/10th as productive in Rust/Go as they are in Visual Studio and C#.

Indeed! This has always mystified me. Why is it so easy to implement what is now considered to be an anti-pattern (inheritance) when it's so boilerplate and annoying to implement composition? Why does C# not have language support for delegating members? Why do I have to buy and use ReSharper just to generate all that boilerplate? It's a constant battle talking to "just get it done" developers about why inheritance is bad.

Inheritance is only considered an anti-pattern by some.

Since the 90's, any good CS book about OOP paradigms had discussions about is-a and has-a and how to make the best use of each, depending on the desired application architecture.

The thing is, such books usually aren't taught on bootcamps.

Inheritance isn’t an anti-pattern in academia. I do part time work as an examiners for CS students, and I see their car/animal examples everywhere in introductionary courses.

When we have interns, they’ll sometimes build things with inheritance. So it’s certainly still a thing.

I’ve yet to see a real world use of it, where you wouldn’t have been better of not using it though. My real world is the relatively boring world of enterprise public sector software, however, and maybe I’m simply oblivious to where inheritance might be worthwhile.

That is the thing, the architect should have a proper understanding of is-a and has-a relations and apply them appropriately.

Initially, VBX only allowed for composition as well, COM introduced interface inheritance with delegation, when one wanted to override a couple of methods, but not the remaining several ones.

And now UWP offers mechanisms to do implementation inheritance in COM, because everyone got tired to write delegating code for is-a relations.

Inheritance and composition are both tools, it is up to each one to learn how to use them appropriately.

Inheritance is an anti-pattern for some. Not for others (eg me).

As with everything it depends how its used.

Sounds like you would find the Trait system in Rust very interesting.

https://play.rust-lang.org/?version=stable&mode=debug&editio...

Traits are okay in principle but, as a Rust beginner, the huge number of trait implementations make browsing the api docs overwhelming. For example, the list of implementations for String don't even fit on the screen at once. [1] It seems very repetitive and I wish there were an easier way to get an overview of what functionality is available and find the right method to call.

[1] https://doc.rust-lang.org/std/string/struct.String.html

It's not a great solution, but I've found it beneficial to lean heavily on the Rust docs search bar when looking for specific behavior. It's very fast, and fuzzy enough that it finds what I'm looking for most of the time.

I'm also a c# dev but with less experience. Could you elaborate? Does the mean you copy paste shared code to all of the derived classes? I think I know why you say it's a maintenance nightmare because you start off with a method or properties that make sense in all of the derived classes but overtime the classes become less cohearant and start to develope warts and it would have been easier to modify the duplicated code.

It’s more that there are other ways to reuse code. Search for “composition over inheritance” in your favourite search engine for more information.

I think you formulate it nicely. Sometimes the things it made sense to share stop making sense.

Something that means rework, sometimes you end up with a parent method which is overridden in every child, possibly because each override was spread out over a long time period and no one bothered to look outside the child.

Inheritance makes sense with interfaces in C# but for the rest I think composition is just a better way of sharing.

Watch out for hype that golang authors and supporters claim without properly backing it up, there's quite a bit of it.

There are other languages that have better support for composition, while still maintaining support for inheritance (e.g. Kotlin). Inheritance has its uses, as evident by the fact that Rust is considering adding support for inheritance (e.g. writing GUIs).

I’m not sure what you mean by “rust is considering adding support for inheritance”; as far as I know that’s not true. Did I forget something? Do you have a link to the proposal?

I came across it a while ago, I think it was mentioned by pcwalton or someone if I'm not mistaken, specifically citing writing GUI code as a rationale. That being said, Rust (and Java, Kotlin, Scala, C#, etc) have default interface method implementations which might alleviate some of the need for full blown inheritance, unlike golang's interfaces.

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