From: Florian Gilcher <flo@...>
Date: 2009-01-24T05:58:23+09:00
Subject: Re: class 'initialize' method not working ???

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On Jan 23, 2009, at 9:09 PM, Tom Cloyd wrote:

> I'm baffled by this error, after a hour+ of experimentation with  
> solutions. I assume it's a compiler error (right term in Ruby?), as  
> I'm not even getting access to ruby-debug.


Its not a ruby error.

> Code snippet:
> =======
> def main
>
> opdb = Open_db.new( [1,2,3] )
>
> end
>
> class Open_db
>   def initialize( dblist )
>     @dbs = dblist
>   end
>
>   @dbs.each do |cnt|  # <= line producing the error
>      db_lbl = cnt[0]
>      db_nm = cnt[1]
>   end
> end
>

That might be irritating at first, but you actually refer to two  
different variables hier.

First, in #initialize, you refer to an instance variable called @dbs  
in the context of an object instance (the instance of Open_db).

The second part with @dbs, which is evaluated when loading the class  
definition is refering to an instance variable in the context of a  
class definition (as classes in ruby are objects by themselves, this  
is perfectly valid). The problem is, that in class context, @dbs has  
not been initialized. Unitialized instance variables are nil by  
definition => calling each on it fails.

Feel free to ask further questions.

Regards,
Florian

- --
Florian Gilcher

smtp:   flo@andersground.net
jabber: Skade@jabber.ccc.de
gpg:    533148E2

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