From: Graham Nicholls <graham@...>
Date: 2004-07-06T16:37:49+09:00
Subject: Initialize returning nil if error condition - how

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

-- 
With Linux, the answer's always "Yes"