新手求教!!!! 如题：ruby 数组的 减法是通过什么判断两个对象是否相等的？自己的类想支持数组减法应该实现哪些方法？
puts "诶呦,这个发帖好高科技啊!!!!"
It compares elements using their hash and eql? methods for efficiency.
[84] pry(main)> show-doc Array#-
From: array.c (C Method):
Owner: Array
Visibility: public
Signature: -(arg1)
Number of lines: 11
Array Difference
Returns a new array that is a copy of the original array, removing any
items that also appear in other_ary. The order is preserved from the
original array.
It compares elements using their #hash and #eql? methods for efficiency.
[ 1, 1, 2, 2, 3, 3, 4, 5 ] - [ 1, 2, 4 ] #=> [ 3, 3, 5 ]
If you need set-like behavior, see the library class Set.