Question

I have a list of Fruit structs called basket. Each Fruit struct has a name (a string) and a calories (an integer). I would like to sort basket so that:

1. The Fruits with the highest calories appear first. For example, a fruit with 500 calories appears before a fruit with 400 calories.

2. If two Fruits have equal calories, the Fruit whose name comes first alphabetically comes first, ignoring case. For example, given two fruits with equal calories, one named “banana” will come before one named “Citrus”.

The definition of Fruit is not something I control so I’d prefer a solution which doesn’t involve mixing anything into Fruit or changing it. Is this possible?

Answer 1

The easy solution is

basket.sort_by { |f| [-f.calories, f.name] }

Of course, if this is the canonical sort order for fruit then it should be defined using the <=> method and with the Comparable module mixed into Fruit