From: Dave Thomas <Dave@...>
Date: 2001-08-24T22:13:57+09:00
Subject: [ruby-talk:20285] Re: Example 1: Was Ruby Article

"Joshua Drake" <jd.nospam@commandprompt.com> writes:

> >
> > I guess my main comments would be:
> >
> > 1. It crashes if the user enters an end of file
> 
> Do you mean if they hit ctrl-d? Or when they type END. When I run the
> script,
> it does not crash if I type END. If you are talking about ctrl-d... how
> would I catch that?

'gets' returns nil on end of file (probably ^d on your box). That's
why you see code like

   break unless line = gets

or

   line = gets ? $_.chop : "END"

or

   line = (gets || "END").chomp

These all work because when Ruby tests a value in a boolean context,
'nil' is interpreted as false.

> > 2. It should probably be chop, not chop!

If you want to modify the line in place, use chop!, which changes the
receiver:

    before: line = "hello\n"

       line.chop!

    after:  line = "hello"

The '!' indicates that the receiver is likely to be changed.

If instead you want to return the value of the text without the last
character, use 'chop'

    fred = line.chop

This leaves 'line' unaltered: fred receives the new value.

Also, it's probably safer to use 'chomp' rather than 'chop'.



Regards


Dave