From: Chad Perrin <perrin@...>
Date: 2007-04-17T04:03:10+09:00
Subject: Re: translate Perl diamond operator to Ruby

On Mon, Apr 16, 2007 at 08:05:05PM +0900, Robert Klemme wrote:
> On 16.04.2007 00:08, Chad Perrin wrote:
> >On Mon, Apr 16, 2007 at 03:40:17AM +0900, Ken Bloom wrote:
> >>On Mon, 16 Apr 2007 03:06:58 +0900, Chad Perrin wrote:
> >>
> >>>Over the years, I've found the following to be an excellent way to whip
> >>>up quick, very useful Perl scripts:
> >>>
> >>>  #!/usr/bin/perl
> >>>
> >>>  while(<>) {
> >>>    # do stuff . . .
> >>>  }
> >>>
> >>>Is there an equivalent idiom in Ruby?  So far as I'm aware, there's no
> >>>catch-all diamond operator in Ruby that allows one to create a default
> >>>input behavior for a script that accepts either a filename or piped
> >>>output of another command the way this works in Perl.  I certainly hope
> >>>there's an equivalent, though.
> >>ARGF.each do |line|
> >>  # do stuff
> >>end
> >
> >Thanks muchly.  Armed with this seed of knowledge (to mix a metaphor), I
> >can find the rest via Google easily.  I appreciate it.
> 
> You can also use one of the command line switches -n or -p, e.g.
> 
> 13:04:42 [tmp]: ls -l | ruby -ne 'puts "<#{$_[0,3]}>"'
> <tot>
> <-rw>
> <lrw>
> 13:04:59 [tmp]:
> 
> Kind regards
> 
> 	robert

That's useful, and very similar to Perl, but in practice I find that I
don't take that approach very often at all.  The only command/shebang
line switch I use with any frequency in Perl is -l, for adding a newline
to the end of all print statements, and since Ruby has puts I don't need
to do that in Ruby.  Usually, the programs I find myself writing don't
neatly fit into a while loop -- except when writing a toy script to
demonstrate something, in which case it usually pays to be explicit with
the while loop anyway -- so the while (<>) { . . . } idiom in Perl (and
now the ARGF.each do |foo| . . . end idiom in Ruby) is far more useful
to me.

-- 
CCD CopyWrite Chad Perrin [ http://ccd.apotheon.org ]
unix virus: If you're using a unixlike OS, please forward
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