红宝石中的三向比较

Question

什么是确保三个变量在ruby中都相等的最简洁方法？例如

dog = 'animal'
cat = 'animal'
chicken = 'animal'
shoe = 'clothing'

# Something like this...which doesn't work
dog == cat == chicken # true   
dog == cat == shoe # false

Answer 1

三个元素最简洁的方法是(抱歉让你失望):

dog == cat && cat == chicken

当然,如果你想......你总能变得聪明......

[dog, cat, chicken] == [dog] * 3
[dog, cat, chicken].uniq.length == 1

...但这并没有真正使代码更简洁(或可读).

如果你想要一个可以比较任意多个元素的可重用函数,我会做这样的事情:

def all_equal?(*elements)
  elements.all? { |x| x == elements.first }
end