From: Carlos <angus@...>
Date: 2005-04-20T22:31:18+09:00
Subject: Re: [ANN] Article: Seeing Metaclasses Clearly

[Jim Weirich <jim@weirichhouse.org>, 2005-04-20 06.15 CEST]
> On Tuesday 19 April 2005 09:29 pm, David A. Black wrote:
> > Although... here's something interesting:
> >
> [... elided IRB session that illustrates that singleton classes have no 
> instances ...]
> 
> Wow ... I didn't see that coming.  That has implications for elsewhere in the 
> thread discussing the Ruby object model diagram where everyone is drawing 
> ASCII art with arrows labeled "instance-of".  All those diagrams are rendered 
> invalid in one fell swoop.  Wow. (I notice that Matz's diagram in the RI docs 
> does not explicitly label the horizontal arrows "instance-of" ).

Wow, it was only me. Since when I am everyone? Thanks for the compliment,
anyway.

Before your discoveries make you jump into conclusions, you should apply a
little of scientific thought. You have two facts: one, that the diagram
shows that Object --instanceof--> (Object). The other: that

$ ruby -e 'p Object.instance_of?(class<<Object;self;end)'
false

One possible explanation for this discrepancy is that the diagram is wrong.
Another is that instance_of? doesn't take into account singleton classes.

I guess it's the second one :).

Good luck.