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Message-ID: <4154A0D5.C117AA80@dessent.net>
Date: Fri, 24 Sep 2004 15:33:57 -0700
From: Brian Dessent <brian AT dessent DOT net>
Organization: My own little world...
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To: cygwin AT cygwin DOT com
Subject: Re: Is setup.exe _supposed_ to delete the cygwin dll before attempting to run shell scripts?
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Reply-To: cygwin AT cygwin DOT com

Igor Pechtchanski wrote:

> > You first get the depth-first order: D, C, B, A.
> 
> <PEDANTIC>
> Properly speaking, the depth-first order will be B, D, C, A...
> </PEDANTIC>

D'oh'

> Unfortunately, this won't work when you have circular dependencies (e.g.,
> cygwin <-> fileutils).

Oh, did I forget to say the graph must be a DAG before starting?  :) 
Anyway, there are heuristics that could be used to find the best
"feedback set" of edges for which removal would result in an acyclic
graph.  e.g. the one described at
<http://www2.toki.or.id/book/AlgDesignManual/BOOK/BOOK4/NODE182.HTM>

> I think Max's solution is probably the least complex short-term one (i.e.,
> run all preremove scripts in batch *before* removing any files, and hope
> for the best).

Yeah, probably true... I realize that people have probably already
suggested these solutions involving graph theory in the past.  And as
you point out, a working patch is one thing, a bunch of conjecture is
another.

Brian

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