From: Gavin Sinclair <gsinclair@...>
Date: 2009-12-25T15:20:26+09:00
Subject: [ruby-core:27321] Re: select!

On Fri, Dec 25, 2009 at 12:05 PM, Ryan Davis <ryand-ruby@zenspider.com> wrote:

>> As a datum: I've frequently typed select! in the past, expecting it to
>> be there, so it _is_ useful to me. �(I then add it myself, of course,
>> but curse having to do so.)
>
> I still don't think the concept makes sense. Sure, you seem to want to use it, but in the same vain do you also reach for delete_if's opposite?
>
> �ary.delete_unless { ... }

No, but how it that in the same vein?  I don't use delete_if (I much
prefer the method name 'reject') and I wouldn't use delete_unless
either, whereas I like, understand and have frequently used select!.

I guess what I'm saying is this: I don't think of select! in terms of
opposites (as in "I use reject! so I'll also use select!").  It's just
as in-place version of "select", as the name implies.

I don't want to labour the point, but this is my typical use case:

Code starts out as something like

  result = collection.map { |x| ... }.select { |x| ... }

But then I might add code to the "map" part, and the code now extends
over a few lines and looks poor if it's chained together.  So it gets
changed to:

  result = collection.map { |x|
    ...
    ...
    ...
  }
  result.select! { |x| ... }

--
Gavin Sinclair