From: Florian Gross <flgr@...>
Date: 2005-03-30T04:59:46+09:00
Subject: Re: attr :<symbol>?

Glenn Smith wrote:

> Here is James' example:
> 
> A simple example
> 
> # Meta-programming
> # Add a public array property to an object instance
> 
> class Meta
>   def self.has_many( sym )
>     attr_tmp = "def  #{sym.to_s} \n"
>     attr_tmp << " @#{sym.to_s} = [] unless @#{sym.to_s}\n"
>     attr_tmp << " @#{sym.to_s}; end"
>     eval ( attr_tmp  )
>   end
> end

And here it is without an eval:

class Meta
   def self.has_many(sym)
     ivar = :"@#{sym}"
     define_method(sym.to_sym) do
       new_value = instance_variable_get(ivar) || []
       instance_variable_set(ivar, new_value)
       new_value
     end
   end
end