From: Robert Klemme <shortcutter@...>
Date: 2006-04-29T20:10:14+09:00
Subject: Re: class returns value without method or attribute

2006/4/29, kris <krisleech@interkonect.com>:
> I like the idea of using inspect, will this also allow me to assign
> value like:
> money = Money.new
> money = 5

No, inspect will only affect output with p (or in IRB).

> Also do I need to add a method for + and -, is there not a module like
> Comparable that I can mixin to get this functionality?

Comparation and arithmetic are two orthogonal concepts, i.e.
completely unrelated. If you want arithmetic in your class, you need
to override +, - and coerce.

http://www.rubygarden.org/ruby?CoerceExplanation
http://www.rubygarden.org/?terms=coerce&submit=SEARCH&handler=searching

For ordering there is mixin Comparable
http://ruby-doc.org/core/classes/Comparable.html
http://www.rubycentral.com/book/ref_m_comparable.html

> Are there any other typical methods I should be adding? Excluding the
> money specific stuff I have to_s.

to_int is an option, too, if your instance is equivalent to an int.
Additionally you should implement to_i and to_f.

Kind regards

robert

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