From: Wybo Dekker <wybo@...>
Date: 2005-06-18T00:40:01+09:00
Subject: Re: stubborn program using readline

On Sat, 18 Jun 2005, James Edward Gray II wrote:

> On Jun 17, 2005, at 9:28 AM, Wybo Dekker wrote:
> 
> > What I need is a translation of this simple Perl example into Ruby -
> > I think Ruby can't do this:
> 
> [snip code]
> 
> I think it can:

Sure, when you run it with a file argument. 
But now try to run it on stdin.
For example:

$ showlines.rb < showlines.rb

It won't work. In Perl, it will. 
 
> #!/usr/local/bin/ruby -w
> 
> require "readline"
> include Readline
> 
> lines = ARGF.readlines
> puts "#{lines.size} lines."
> 
> loop do
> line = readline("Line number:  ", true)
> 
> if line !~ /^\d+$/
>    puts "Please enter a positive integer."
> else
> number = line.to_i
> case number
> when 0
>    break
> when 1..lines.size
>    puts "Line #{number}:  #{lines[number - 1]}"
> else
>    puts "No such line."
>    end
>     end
> end
> 
> __END__
> 
> My run:
> 
> $ ruby showlines.rb showlines.rb
> 25 lines.
> Line number:  1
> Line 1:  #!/usr/local/bin/ruby -w
> Line number:  16
> Line 16:                case number
> Line number:  17
> Line 17:                when 0
> Line number:  18
> Line 18:                        break
> Line number:  1003
> No such line.
> Line number:  darn
> Please enter a positive integer.
> Line number:  0
> 
> Hope that helps.
> 
> James Edward Gray II
> 
> 

-- 
Wybo