From: Jacob Fugal <lukfugl@...>
Date: 2005-10-06T06:18:59+09:00
Subject: Re: select! not present but reject! is

On 10/5/05, Gene Tani <gene.tani@gmail.com> wrote:
> Can you use Enumerable#partition  ?
>
> Geert Fannes wrote:
> > Hello, is there a reason why I can find the in-place mutator method
> > Array#reject! and not Array#select! ? It is ofcourse easy to add this
> > method but it is my feeling this should be added to the core.

That's beside the point, for two reasons:

1) Geert's question is regarding the lack of symmetry between the
presence of Array#reject! but absence of Array#select!.[1]

2) Geert is interested in in-place mutators (Array#reject!,
Array#select!). Enumerable#partition returns two new Arrays; it is not
an in-place mutator.

As far as work-arounds, this would probably be closest:

  class Array
    def select!
      self.reject! { |e| not yield e }
    end
  end

But I'm sure Geert is already aware of this (or a better version).
Geert's question, to which I would like an answer as well, is this:

Is there a reason Array#select! doesn't exist in the core?

Jacob Fugal