From: Wybo Dekker <wybo@...>
Date: 2005-06-17T23:28:54+09:00
Subject: Re: stubborn program using readline

On Fri, 17 Jun 2005, Jonathan Paisley wrote:

> On Fri, 17 Jun 2005 08:41:22 +0900, Wybo Dekker wrote:
> 
> > On Thu, 16 Jun 2005, Logan Capaldo wrote:
> > 
> >> Theory: readline reads from STDIN correct? using rltest < rltest means
> >> that STDIN gets EOF, which means STDIN is closed which means readlien
> >> can't read anything from it.
> > 
> > No, readline should not necessarily read from STDIN. It can read from the 
> > console, /dev/tty or so. 
> 
> Since you always want to readline from the terminal, try that:
> 
>   tty = open("/dev/tty","a+")
>   tty.readline

That's too simple: it does not use the readline library with its editing 
and completion facilities.

What I need is a translation of this simple Perl example into Ruby - 
I think Ruby can't do this:

    #!/usr/bin/perl -w
    
    # showline - read lines from stdin (either file or pipe),
    #            then let user interrogate lines by number
    
    use Term::ReadLine;
    
    push(@x,$_) while <>;
    print scalar(@x)," lines\n";
    
    $t=new Term::ReadLine 'vpp';
    
    while (1) {
       $_ = $t->readline("type line number (0 to stop): ");
       PROMPT: {
          /^\d+$/ or  do { print "Not a positive number\n"; last PROMPT};
          $_ > @x and do { print "No such line\n";          last PROMPT};
          $_      and do { print "line $_: $x[$_-1]";       last PROMPT};
          die "thanks!\n";
       }
    }

Typical run:

$ showline <showline
21 lines
type line number (0 to stop): 1
line 1: #!/usr/bin/perl -w
type line number (0 to stop): 3
line 3: # showline - read lines from stdin (either file or pipe),
type line number (0 to stop): 20
line 20:    }
type line number (0 to stop): 30
No such line
type line number (0 to stop): 0
thanks!
$

-- 
Wybo