From: Gavin Sinclair <gsinclair@...>
Date: 2004-11-30T10:32:24+09:00
Subject: Re: Seeking advice on some method names

On Tuesday, November 30, 2004, 1:52:49 AM, itsme213 wrote:

>> But I don't think Enumerable#one? and Array#one are complementary;
>> they seem entirely different.

> Array#one {|x| pred} would complement Enumerable#one? {|x| pred}
> so
> Array#one
>     is same as Array#one{|x|true}
>     which complements Enumerable#one?{|x|true}

>> Likewise with Array#any: it's useful, but really has nothing to do
>> with #any?

> Array#any{|x| pred} complements Enumerable#any? {|x| pred}
> so
> Array#any complements Enumerable#any?{|x|true}


Two equivalent code samples:

 A)

    numbers.one { |n| n.prime? }
    numbers.any { |n| n.prime? }

 B)

    numbers.select { |n| n.prime? }.only
    numbers.select { |n| n.prime? }.rand

I find (B) more intuitive.  I'd rather see #select doing the
selection, instead of introducing yet more methods that select
elements. [1]  Further, #rand and #only are telling me what
they're doing.  #one and #any are "merely" complements of
#one? and #any?.

To expand further, I find #any quite reasonable, but #rand more so.
Array#rand is something I've implemented occasionally, and have seen
other requests and references.  I find #one quite uncompelling,
because it sounds like #any: it doesn't express its one_and_only_one
meaning.

Cheers,
Gavin

[1] There are valid reasons to introduce more selection methods, but
these don't qualify, to my mind.