From: Joel VanderWerf <vjoel@...>
Date: 2004-10-26T07:31:28+09:00
Subject: Re: Question on defining hier error types: Is this OK?

jim@freeze.org wrote:
> Hi
> 
> I was defining a hierachical error type today and realized
> that I had inheritied from a class before it was closed.
> 
> It seems to work nicely, but was just wondering why.
> 
> Below is an example:
> 
>   module A
>   
>     class MyClassError < StandardError
>       class NoBlockError < MyClassError; end
>       class IOError      < MyClassError; end
>       ...
>     end#class MyClassError
>     
>     
>     class MyClass
>       ...
>       raise MyClassError::NoBlockError
>       ...
>       raise MyClassError::IOError
>       ...
>     end#class MyClass
>     
>   end#module A
>   
> I like the way this turned out. Does anyone see a problem with doing this?
> 

My guess: Closing a class isn't really significant, since it can be 
reopened at any time. The class has been fully defined when the "class 
XXX < ..." line has been executed. For consistency, the following would 
have to be equivalent:

   class A
     do_something_with_A
   end

and

   class A
   end # close the class

   class A
     do_something_with_A
   end