From: Joseph McDonald <joe@...>
Date: 2000-12-04T15:10:02+09:00
Subject: [ruby-talk:6795] Re: using join()

Thanks.

You guys are great!  You're right, I was thinking in perl.
the habits are hard to break.

I can't wait for the book.  I hope you guys aren't getting
sick of my questions until I get it.

Here's a prob I just tumbled into.  During debugging
it would be cool to do something like:


def printvars (args)
  args.each do |obj|
     print obj.name, "=", obj, "\n";
  end
end

urls = ["hello", "world"]
text = "world!"
printvars([urls, text])

but I can't seem to get the objects name.

thanks,
-joe


"David Alan Black" <dblack@candle.superlink.net> wrote in message
news:Pine.LNX.4.21.0012032312040.8861-100000@candle.superlink.net...
> Hello --
>
> On Mon, 4 Dec 2000, Joseph McDonald wrote:
>
> > while I await the "Programming Ruby" book.  Can someone tell me what
> > I'm doing wrong here:
> >
> > i = j = 2
> > a = join(":",i,j);
> > print a
> >
> > undefined method `join' for #<Object:0x8106cd8> (NameError)
>
>
> Yes: you're writing Perl :-)
>
> join is an instance method of class Array.  Therefore, you need
> an array object, so that you can call its join method.  For
> example:
>
>   i = j = 2
>   a = [i,j].join ':'   # =>  "2:2"
>
> This is different from Perl, where join is a universal function which
> takes its second and subsequent arguments as the things to join.
> Ruby's join only takes one argument, the separator.  What gets joined
> are the elements of the array on which the method is called (i.e.,
> the "receiver" of the join "message").
>
> (By the way, note that in the above example, the 2's get conveniently
> turned into strings.  That happens to happen with join; it isn't
> generally automatic in Ruby as it is in Perl, though.)
>
> > also, is it true that this:
> >
> > s/^\s+|\s+$//   # trim whitespace
> >
> > doesn't work?
> >
> > when I changed it to:
> >
> >  line = $_
> >  line.sub!(/^\s+|\s+$/ , "") # trim whitespace
> >
> > it appeared to work.  Just wondering if s/// works in ruby and I'm doing
it
> > wrong.  I also tried $_ =~ s/^\s+|\s+$//
>
> There's no s/// operator in Ruby: you're right to use [g]sub[!].
> Also, in this particular case you can save yourself some typing:
>
>   line.strip!
>
> will do it.
>
> You'll love the book.
>
>
> David
>
> --
> David Alan Black
> home: dblack@candle.superlink.net
> work: blackdav@shu.edu
> Web:  http://pirate.shu.edu/~blackdav
>
>
>