Feature #18395
Updated by mame (Yusuke Endoh) over 2 years ago
PR: https://github.com/ruby/ruby/pull/5110#issuecomment-984345309
It is common to use `-=` to modify an array to remove elements. Also, there is `Array#difference` which accepts multiple arguments. Both of these methods allocate an intermediate array when the original array could be re-used.
I am proposing we add an API onto Array that allows the programmer to perform a subtraction/difference operation and mutate the original array.
I am proposing `Array#subtract!`. Reasons why I did not choose `Array#difference!` are discussed in the comments of the PR. I'm also happy to discuss alternative names.
```
ary = [0, 1, 1, 2, 1, 1, 3, 1, 1]
ary.subtract!([1]) #=> [0, 2, 3]
ary #=> [0, 2, 3]
ary = [0, 1, 2, 3]
ary.subtract!([3, 0], [1, 3]) #=> [2]
ary #=> [2]
```