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Date: Wed, 5 Dec 2001 15:25:53 -0500 (EST)
From: Pengcheng Wu <wupc@ccs.neu.edu>
To: Doug Orleans <dougo@ccs.neu.edu>
cc: Karl Lieberherr <lieber@ccs.neu.edu>, skotthe@ccs.neu.edu,
   edwards@intranet.com, johan@ccs.neu.edu, john_j_sung@yahoo.com,
   neerajsangal@mediaone.net, robby@ccs.neu.edu
Subject: Re: contracts and AOP
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One of the problems with the aspects that invalidate pre- and
post- conditions of existing code is that the end-user programmers
have to know how many aspects are related to the code and how they
are related to the code(in what way they change the pre- and post-
conditions), and the aspects can not be freely attached to or
detached from the base program, which may undermine the objective
of AOP to separate concerns.

--Pengcheng


On Wed, 5 Dec 2001, Doug Orleans wrote:

> Karl Lieberherr writes:
>  > Doug proclaimed the following guidelines:
>  > 
>  > Adding an aspect should not change (invalidate?)
>  > pre- and post- conditions of existing code.
>  > 
>  > Adding an aspect should lead to a behavioral subtype.
> 
> I think "proposed" is a better word than "proclaimed".  Or more like,
> "hypothesized".  I think Theo is right, it depends on the aspect.
> Perhaps that would be a way to categorize aspects: those that preserve 
> contracts and those that invalidate contracts, without making a value 
> judgement on the latter category.
> 
> --Doug
>