From: Robert Klemme <bob.news@...>
Date: 2004-07-06T17:37:38+09:00
Subject: Re: Initialize returning nil if error condition - how


"Graham Nicholls" <graham@rockcons.co.uk> schrieb im Newsbeitrag
news:40ea5761$0$15264$afc38c87@auth.uk.news.easynet.net...
> Graham Nicholls wrote:
>
> > I've got "The Ruby Way" & "Programming Ruby", but can't find out how
to
> > have an initializer return nil if theres a problem - something like
this:
> >
> > Class Cover_file
> > def initialize(fname)
> >      64     @fname=fname
> >      65     if $verbose
> >      66       printf("Checking file %s\n",@fname)
> >      67     end
> >      68     # Parse filename for component parts
> > (product,policy_no,site_no,schedule)
> >      69     comp_patt=Regexp.compile(/^([A-Z]+)([0-9]+)([0-9][0-9]
> > ([\w\d]+)\.en$/)
> >      70     if @fname !~ comp_patt
> >      71       if $verbose
> >      72         printf("Sorry, %s does not match cover clause filename
> > template\n",fname)
> >      73       end
> >      74       return nil
> >
> > If I try self=nil, I (not unreasonably - I expected it) get an error.
> >
> > What I want to do is this:
> >
> >         cfile=Cover_file.new(fname)
> >         if cfile == nil
> >                 some error handling
> >         end
> >
> > But I can't work out how.
> > Thanks.
> > Graham Nicholls
> >
> Just had an idea (thats the 2nd time I've done that this week! (not had
an
> idea, fools, commented on my own post!).  I'm supposed to raise an
error,
> aren't I?

Yes, that's the proper way to deal it.  Exceptions make code much cleaner
if properly used.

Regards

    robert