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Asked: 2026-05-11T05:12:24+00:00

Given a set of tuple classes in an OOP language: Pair, Triple and Quad,

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Given a set of tuple classes in an OOP language: Pair, Triple and Quad, should Triple subclass Pair, and Quad subclass Triple?

The issue, as I see it, is whether a Triple should be substitutable as a Pair, and likewise Quad for Triple or Pair. Whether Triple is also a Pair and Quad is also a Triple and a Pair.

In one context, such a relationship might be valuable for extensibility – today this thing returns a Pair of things, tomorrow I need it to return a Triple without breaking existing callers, who are only using the first two of the three.

On the other hand, should they each be distinct types? I can see benefit in stronger type checking – where you can’t pass a Triple to a method that expects a Pair.

I am leaning towards using inheritance, but would really appreciate input from others?

PS: In case it matters, the classes will (of course) be generic.

PPS: On a way more subjective side, should the names be Tuple2, Tuple3 and Tuple4?

Edit: I am thinking of these more as loosely coupled groups; not specifically for things like x/y x/y/z coordinates, though they may be used for such. It would be things like needing a general solution for multiple return values from a method, but in a form with very simple semantics.

That said, I am interested in all the ways others have actually used tuples.

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  1. Different length of tuple is a different type. (Well, in many type systems anyways.) In a strongly typed language, I wouldn’t think that they should be a collection.

    This is a good thing as it ensures more safety. Places where you return tuples usually have somewhat coupled information along with it, the implicit knowledge of what each component is. It’s worse if you pass in more values in a tuple than expected — what’s that supposed to mean? It doesn’t fit inheritance.

    Another potential issue is if you decide to use overloading. If tuples inherit from each other, then overload resolution will fail where it should not. But this is probably a better argument against overloading.

    Of course, none of this matters if you have a specific use case and find that certain behaviours will help you.

    Edit: If you want general information, try perusing a bit of Haskell or ML family (OCaml/F#) to see how they’re used and then form your own decisions.

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