Why use tuples instead of objects?

Question

The codebase where I work has an object called Pair where A and B are the types of the first and second values in the Pair. I find this object to be offensive, because it gets used instead of an object with clearly named members. So I find this:

List<Pair<Integer, Integer>> productIds = blah(); // snip many lines and method calls  void doSomething(Pair<Integer, Integer> id) {   Integer productId = id.first();   Integer quantity = id.second(); } 

Instead of

class ProductsOrdered {   int productId;   int quantityOrdered;   // accessor methods, etc }  List<ProductsOrderded> productsOrdered = blah(); 

Many other uses of the Pair in the codebase are similarly bad-smelling.

I Googled tuples and they seem to be often misunderstood or used in dubious ways. Is there a convincing argument for or against their use? I can appreciate not wanting to create huge class hierarchies but are there realistic codebases where the class hierarchy would explode if tuples weren't used?

Answer 1

First of all, a tuple is quick and easy: instead of writing a class for every time you want to put 2 things together, there's a template that does it for you.

Second of all, they're generic. For example, in C++ the std::map uses an std::pair of key and value. Thus ANY pair can be used, instead of having to make some kind of wrapper class with accessor methods for every permutation of two types.

Finally, they're useful for returning multiple values. There's really no reason to make a class specifically for a function's multiple return values, and they shouldn't be treated as one object if they're unrelated.

To be fair, the code you pasted is a bad use of a pair.