From: Robert Klemme <shortcutter@...>
Date: 2008-11-04T21:43:31+09:00
Subject: Re: Conditional overriding of operators

2008/11/4 Daniel Vartanov <daniel.vartanov@gmail.com>:
> I am trying to replace .+ operator of Numeric class if and only if
> argument (summand) is my own class.
>
> To be more specific: I am writing geometry module in Ruby and need to
> implement vector-number multiplication so that both:
>
> 2 * vector
> vector * 2
>
> work well.
>
> Therefore I need to replace .+ method of Numeric without spoiling
> arithmetical operations with other classes.

No, you don't.  You need to implement #coerce and #+, #- etc. in
*your* class properly (see the link Pit provided for one, albeit not
very complete example). Basically your coerce is invoked when Fixnum#+
sees an instance of your class so you are in control what operation is
finally implemented.

You can find more hits with
http://blade.nagaokaut.ac.jp/cgi-bin/vframe.rb?key=coerce&cginame=namazu.rb&submit=Search&dbname=ruby-talk&max=50&whence=0

Cheers

robert

-- 
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