Path: utzoo!attcan!uunet!wuarchive!zaphod.mps.ohio-state.edu!usc!apple!vsi1!indetech!pacbell!m5!tma
From: tma@m5.COM (Tim Atkins)
Newsgroups: comp.object
Subject: Re: Visibility in Booch's book
Message-ID: <3973@m5.COM>
Date: 5 Nov 90 21:10:15 GMT
References: <21243@well.sf.ca.us> <717@ajpo.sei.cmu.edu>
Reply-To: tma@m5.UUCP (Tim Atkins)
Distribution: comp
Organization: Object Sciences Corp., Menlo Park, CA
Lines: 20

In article <717@ajpo.sei.cmu.edu> gbooch@ajpo.sei.cmu.edu (PUT YOUR NAME HERE) writes:
>The reverse is indeed true (a few others have pointed this out, and the bug 
>will be fixed in the next printing). I and my copyeditor
>apparently missed this reversal.
>
>if object X of class A sends a message to object Y of B, then it must
>be the case that class A in some manner has visibility to class B. this
>visibility may be achieved via a using relationship, or via an inheritance relationship.
>
>egb

	This may be a minor quibble or it may be that I'm missing the
	point you are trying to make here.  The phrase "has visibility
	to" seems to me somewhat synonymous with "is visible to".  If
	this is in fact the case then it seem that in the above, 
		B "is visible to" A 
	but not the reverse.  With inheritance in the picture then this
	visibility may be quite indirect.
	 
	What am I missing?