From: Dave Thomas <dave@...>
Date: 2003-12-08T22:48:48+09:00
Subject: Re: subclassing Errno::XXX


On Dec 8, 2003, at 2:47, Yukihiro Matsumoto wrote:

> I'm not sure what you mean.  Do you mean when MissingFileError
> inherits from Errno::ENOENT, it should inherit Errno constat from
> Errno::ENOENT as well?

I'm not addressing Nobu's point, but there is an argument to say that 
there is no meaningful inheritance at all if you _change_ Errno: that 
is, if you subclass an Errno::Xxx, the Errno constant in the subclass 
must be identical to that in the parent (otherwise it isn't a true 
subclass). After all, these classes are essentially wrappers for the 
Errno value, and so for a subclass to maintain the "isa" relationship 
it must wrap the same value too.

Cheers

Dave