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Generics in Java are giant hack from the early 2000’s to maintain backwards compatibility with 1990’s-vintage JVMs. C#’s generics we’re done right.

eropple 7y ago
I'm of two minds of that, these days. I came from C# so of course reified generics were of course better, of course--but these days I would rather have them in Java more and in C# less. I often find myself wanting to write the moral equivalent of `IFoo<?>` in C# and end up having to have two separate interfaces, etc. just to have a way to handle a list of a thing that I end up working on in an abstract manner. (Though I'd caveat that that is more of a gamedev-related concern than in Java/Kotlin, which I write for work.) I do appreciate, though, that when Microsoft decided to do generics for C#, they did so decisively. These days, when C# gets a new feature, it seems like it's the complete opposite of decisively delivered.
- jimmaswell 7y ago
  You mean like this, right? class A {}; class A<T> : A {}; I don't mind that. It can even be an aid to organization - all the generic stuff goes in the generic class, all the stuff that doesn't rely on that can go in the base class. But it would be nice to use something like <?>. Too bad generics don't inherit implicit casts, like A<int> to A<object>.
  - eropple 7y ago
    I do mean that, and I do mind it a lot when I'm so used to just being able to erase the generic. There are performance implications to type erasure, to be sure, but when our computers are mostly all future machines from beyond the moon, I'm more interested in minimizing the impedance between my brain and a solved problem.
    - jimmaswell 7y ago
      This is the only non-bad consequence of type erasure I'm aware of. On the other hand, a lot of code I've written in C# would be impossible or severely hacky without type retention, like "new T()", "T is Thing", finding all classes that are derived from T, etc.
      - eropple 7y ago
        TBH, I'm just as happy passing a factory method in for that sort of thing. Because it allows you to do both and pick the one that makes the most sense for you in a given situation.

eropple 7y ago

I'm of two minds of that, these days. I came from C# so of course reified generics were of course better, of course--but these days I would rather have them in Java more and in C# less. I often find myself wanting to write the moral equivalent of `IFoo<?>` in C# and end up having to have two separate interfaces, etc. just to have a way to handle a list of a thing that I end up working on in an abstract manner. (Though I'd caveat that that is more of a gamedev-related concern than in Java/Kotlin, which I write for work.) I do appreciate, though, that when Microsoft decided to do generics for C#, they did so decisively. These days, when C# gets a new feature, it seems like it's the complete opposite of decisively delivered.

jimmaswell 7y ago
You mean like this, right? class A {}; class A<T> : A {}; I don't mind that. It can even be an aid to organization - all the generic stuff goes in the generic class, all the stuff that doesn't rely on that can go in the base class. But it would be nice to use something like <?>. Too bad generics don't inherit implicit casts, like A<int> to A<object>.
- eropple 7y ago
  I do mean that, and I do mind it a lot when I'm so used to just being able to erase the generic. There are performance implications to type erasure, to be sure, but when our computers are mostly all future machines from beyond the moon, I'm more interested in minimizing the impedance between my brain and a solved problem.
  - jimmaswell 7y ago
    This is the only non-bad consequence of type erasure I'm aware of. On the other hand, a lot of code I've written in C# would be impossible or severely hacky without type retention, like "new T()", "T is Thing", finding all classes that are derived from T, etc.
    - eropple 7y ago
      TBH, I'm just as happy passing a factory method in for that sort of thing. Because it allows you to do both and pick the one that makes the most sense for you in a given situation.