From: Gavin Sinclair <gsinclair@...>
Date: 2004-06-18T23:56:41+09:00
Subject: Re: How to make generic #== method?

On Saturday, June 19, 2004, 12:28:21 AM, Florian wrote:

> Moin!

> Joel VanderWerf wrote:

>> module ContentEquality
>>   def hash
>>     content.hash
>>   end
>> 
>>   def eql?(other)
>>     content.eql? other.content
>>   end
>> 
>>   def ==(other)
>>     # self.class == other.class and # optional
>>     content == other.content
>>   end
>> end

> That's cool, I think I'm going to use it in the future! :)

>> Another way might be to iterate over a list of instance variables (or
>> all of 'em, if that's what you want).

> Hm, maybe a default .content could be provided by the module; it could
> look like this:

> module ContentEquality
>    def content
>      instance_variables.map { |name| instance_variable_get(name) }
>    end
> end

Because this discards the instance variable names, some pathological
cases would give false positives.  Better to make #content return a
hash instead.

Gavin