From: "Berger, Daniel" <Daniel.Berger@...>
Date: 2005-03-23T02:17:34+09:00
Subject: Re: RCR 296: Destructive methods return self

> -----Original Message-----
> From: Malte Milatz [mailto:malteNOSPAM@gmx-topmail.de] 
> Sent: Tuesday, March 22, 2005 10:00 AM
> To: ruby-talk ML
> Subject: Re: RCR 296: Destructive methods return self
> 
> 
> Christian Neukirchen:
> >>>     gsub!  returns self
> >>>     gsub!? returns self or nil  (yes, it looks silly)
> > I actually like that. :-)
> 
> +1
> 
> Malte

Hm...actually this reminds me of a Perl module called "Want" by Robin
Houston.  With that module, you could get extremely fine control over
calling context.  For example, you could do a sort of "lookahead" to, in
effect, see if the method was chained or not:

use Want;

sub foo{
   ...
   if(want("OBJECT")){
      return $self;
   }
   else{
      # return some other value based on context
   }
}

I used this module in my Set::Array, Set::Hash and Set::String Perl
modules and was quite happy with it.

Could something like "object_wanted?" be added?  Then you, the code
writer, could solve the "self or nil" issue yourself like this:

class Foo
   def some_method!
      if object_wanted?
         return self
      end
      # otherwise, return nil (or whatever)
   end
end

You can take a look at Want at
http://cpansearch.perl.org/~robin/Want-0.08/Want.pm

Just a thought.  Now I suppose someone is going to tell me you could do
this all along. ;)

Regards,

Dan