From: ara.t.howard@...
Date: 2006-03-19T08:11:59+09:00
Subject: Re: can you enable coercion between types?

On Sun, 19 Mar 2006, larry wrote:

> I have a ruby class called Duration that represents a unit of time.
> It's main attribute is a number that represents the duration in
> seconds.
>
> If I try to save it to a DB using Rails, I get a "Duration can not be
> coerced into Float" error.  Is there a way to modify the definition of
> Duration to enable automatic coercion into a float?  (I'm thinking of
> something like adding a  "to_float" method to the class.)
>
> thanks in advance
> larry

try this:

     harp:~ > cat a.rb
     class Duration
       def initialize seconds
         @seconds = seconds
       end
       def coerce other
         if other.class == @seconds.class
           [@seconds, other]
         else
           [Float(@seconds), Float(other)]
         end
       end
     end

     p(40.0 + Duration::new(2.0))
     p(40 + Duration::new(2))


     harp:~ > ruby a.rb
     42.0
     42

hth.

-a
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