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Feature #18395

Updated by mame (Yusuke Endoh) 7 months 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] 
 ```

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