From: Brad <BCoish@...>
Date: 2004-01-01T00:16:47+09:00
Subject: Re: Overriding to_s

ts wrote:

> >>>>> "B" == Brad  <BCoish@Dymaxion.com> writes:
> 
> B> Is there a way to override the to_s method such that it takes a
> B> parameter?  For example, if I wanted to provide a format specifier 
> B> for a number:
> 
>  well, you have several problems
> 
> B>     class Numeric
> 
>  #to_s is defined in Integer, Float, Bignum, ... not in Numeric
> 
>  If you define it in Numeric, ruby will use the old definition in 
>  Integer, ...
> 
> B>         def to_s(optFormat)
> 
>  you are saying that #to_s must have a parameter, this mean that you can't 
>  call it 12.to_s
> 
>  Perhaps best to write it
> 
>            def to_s(optFormat = nil)
> 
>  now Integer#to_s can take an optional argument, this mean that your new
>  method #to_s is not really adapted for Integer (except if format_number
>  take this in count)
> 
> B>             if !optFormat.nil?
> B>                 # format a string based on the optFormat format  
> B>                 # specifier.
> B>                 retVal = format_number(self,optFormat)
> B>             else
> B>                 retVal = self.to_s
> 
>  here, you call recursively #to_s.
> 
>  Perhaps best to alias #to_s before redefining it, and call the alias
> 
> B>             end
> B>             retVal
> B>         end
> B>     end
> 
> 
> Guy Decoux
> 
> 
> 
> 

Guy:

Thanks for the speedy response!  

I guess I was being a bit naive, I thought Numeric was a base class
for Integer, Float, etc.  Is there any way to redefine to_s across
the board, i.e. for Integer, Float, etc without having to duplicate
code for each numeric type?

Yeah, the code is pretty shabby :,.  I didn't put much thought into it
as it was only meant to be an illustration.  Don't get me wrong though
you're points are very good and obviously are not part of my native
ruby thinking, otherwise the sample would have included them.  Thank
you. :)


Hopefully I don't sound rude. :/

Regards,
Brad