From: "Derrick B." <lists@...>
Date: 2012-12-21T03:23:16+09:00
Subject: Re: Perl to Ruby: regex captures to assignment.

Robert Klemme wrote in post #1089733:
>
> I would choose a completely different approach: I would have a single
> expression for matching and decide which assignments to make based on
> the value of one of the capturing groups in the conditional branch:
>
> ["1 3/4", "5"].each do |s|
>   puts s
>
>   if %r{\A(\d+)(?:\s+(\d+)/(\d+))?\z} =~ s
>     w, n, d = $2 ? [$1.to_i, $2.to_i, $3.to_i] : [1, $1.to_i, 0]
>     printf "%4d %4d %4d\n", w, n, d
>   else
>     $stderr.puts "No match #{s}"
>   end
> end
>
> I also spiced the regexp a bit more to be more restrictive.
>

I am prompting for input, so I would be parsing individual strings and
not a list of them.  Though I will remember that for future static
testing.  Also, I and using the "\S+" to handle negative rational
numbers: "-1 3/4".

>
> If you like readability then why are you using Perl in the first place?
> :-)
>

Because Perl is awesome!  That is why I chose Ruby as my next personal
choice of languages to learn.  I just completed a quarter of Programming
Language Concepts where I was introduced to Lisp, but was also required
to use some Python.  I know Python is a fascinatng language, but I am
not yet a big fan of it.  The final assignment was write a class to work
with fractions.  It started as a C++ class, then migrated to Perl (for
fun), and now Ruby (more fun).

I attached the two versions, Ruby and Perl.  The Perl version uses a
"class", also.  Feel free to suggest how to make the Ruby version more
Ruby-ish!  My goal is to take more advantage of the OO aspects of Ruby,
and not just have it look like Perl.

Thanks,

Derrick

Attachments:
http://www.ruby-forum.com/attachment/7988/ratnum.rb
http://www.ruby-forum.com/attachment/7989/ratnum.pl


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