From: Gavin Sinclair <gsinclair@...>
Date: 2005-10-08T10:46:50+09:00
Subject: Re: select! not present but reject! is


David A. Black wrote:
> On Sat, 8 Oct 2005, Jacob Fugal wrote:
>
> > On 10/7/05, Mark Hubbart <discordantus@gmail.com> wrote:
> >
> >> Also, I'm not really advocating any action here. I'm just suggesting
> >> that it would be a little weird for "select!" to be the exact opposite
> >> of "reject!", since the Ruby definitions wouldn't stand up to the
> >> English ones.
> >
> > I'll concede that, but IMNSHO consistency between the non-bang and
> > bang versions seems more important.
>
> The most important thing, though, is that every method name be
> appropriate.  If select! ("dangerous select") is the best way to
> communicate the "delete unless..." process, then it's right.  If not,
> then not.  It's reasonable to expect that a/b == a!/b! -- but the
> existence of a, b, and a! doesn't mean that b! is a good method name
> for the inverse of a!.

Perhaps not, but in this case, inconsistency would be unforgivable.
You should be able to predict how a method will work based on your
knowledge of how other, similar methods work.

In this case it's absolutely clear.

  arr = (1..10).to_a
  arr.map! { |n| n*n }  # -> arr == [1,4,9,...,100]; self is returned

  arr = (1..10).to_a
  arr.reject! { |n| n % 3 == 0 }  # -> arr == [1,2,4,5,7,8]; self is
returned

  arr = (1..10).to_a
  arr.select! { |n| n % 2 == 0 }  # -> arr == [1,3,5,7,9]; self is
returned

It's a no-brainer.  Consistency is paramount!

Cheers,
Gavin