Feature #10729: Array method to subtract in place

• Status: Open
• Assignee: -
• Target version: -

[sawa (Tsuyoshi Sawada)]

I request a method on array that takes another array, subtract that from self in place (= destructively), and return the subtracted elements:

a = [1, 2, 3, 4, 5]
a.some_method([2, 4, 6]) #=> [2, 4]
a #=> [1, 3, 5]

Ideally, it should also allow a block:

a = [1, 2, 3, 4, 5]
a.some_method(&:even?) #=> [2, 4]
a #=> [1, 3, 5]

This operation is quite frequent, but at the moment, it requires several steps to do.

[Eregon (Benoit Daloze)]

The block form can be achieved with Enumerable#partition.

I agree in general splitting an array, according to some property using the order of the elements (no take_drop_while) or to some other array (this request) is more difficult than it could be.