From: Hal Fulton <hal9000@...>
Date: 2003-12-09T05:13:40+09:00
Subject: Re: subclassing Errno::XXX

Dave Thomas wrote:
> 
> 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.

If that's the case, maybe it should be a reader class method wrapping
an anonymous constant?

Hal