From: "David A. Black" <dblack@...>
Date: 2007-03-26T07:31:54+09:00
Subject: Re: Suggestion: swap name of "puts" and "print" and rename "puts" to "put_s"

Hi --

On 3/25/07, Brian Candler <B.Candler@pobox.com> wrote:
> > irb(main):006:0> $_ = "abcdef"
> > => "abcdef"
> > irb(main):007:0> puts "xxx" if /abc/
> > (irb):7: warning: regex literal in condition
> > xxx
> > => nil
> > irb(main):008:0> puts "xxx" if /ghi/
> > (irb):8: warning: regex literal in condition
> > => nil
> >
> > Ugh. So the rule which says "anything which is not 'nil' or 'false' is true"
> > is broken in this construct, and this is just to make ruby more perlish.
>
> Hmm. Thinking about this a bit more: since this applies only to regexp
> *literals*,
>
>    do_something if /foo/
>
> would not be of any use if it were semantically equivalent to
>
>    do_something if true

When I first saw this:

  irb(main):001:0> puts "yes" if a = 1
  (irb):1: warning: found = in conditional, should be ==

I found it annoyingly micromanaging -- until I saw that it only
happened with literals, and then I realized that it was being very
shrewd.  It's interesting, then, that this non-construct can be used
to do the $_ thing.  I wonder whether other cases, like if a = 1, are
going to pressed into service :-)  I hope not; I think the fact that
the regex one warns you and then goes ahead and does something other
than what it's warning you against suggests it could get pretty ugly.

> So I started thinking along the lines of: instead of using global variable
> $_ as a kind of temporary register to pass data between methods, how could
> this construct be made more Rubyish? For example, like a case statement,
> "if /foo/" could translate to "if /foo/ === self" ?
>
> But then I realised: perhaps this is all just a marketing scam. Maybe $_ and
> friends exist in the language, not because they have any real use, but just
> to sucker in Perl programmers. They see them there, and think "great, this
> is like Perl, I'll give Ruby a try". Once they're hooked, they won't use
> them any more than the rest of us do.
>
> If that's true, the construct clearly *has* to use $_ to fulfil its purpose
> :-)

I'd love to see some of the Perl stuff disappear, and it's perenially
in the Ruby TODO file.  I can hardly think of a case where I've seen
anyone use $_ in Ruby.


David

-- 
Q. What is THE Ruby book for Rails developers?
A. RUBY FOR RAILS by David A. Black (http://www.manning.com/black)
   (See what readers are saying!  http://www.rubypal.com/r4rrevs.pdf)
Q. Where can I get Ruby/Rails on-site training, consulting, coaching?
A. Ruby Power and Light, LLC (http://www.rubypal.com)