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Re: [Axiom-developer] build-improvements and latex

From: Waldek Hebisch
Subject: Re: [Axiom-developer] build-improvements and latex
Date: Wed, 8 Nov 2006 12:52:44 +0100 (CET)

> "Page, Bill" <address@hidden> writes:
> [...]
> | However pamphlet files with multiple chunks interact badly with
> | the make dependency processing since changing or adding a single
> | chunk in a pamphlet file triggers re-extraction of all files
> | dependent on that pamphlet and subseqent dependent make processing.
> Like for most (all?) generated files, there is a way out within the
> GNU build system:  change a file only if its content really changed.
> Use the move-if-change script.  
> It is on the list of things to do for build-improvements.

move-if-change solves only part of the problem: if you have a file
which has dependency newer than the file itself make will try
to rebuild the file on _every_ run.  Even if extraction is not very
expensive the cost of extracting and then discarding exctracted version
may quickly accumulate.  AFAICS within make paradigm one would need
_two_ times: modification time and update time.  File needs update
if its update time is before modification time of one of its dependencies.
However, if update do not change file content only update time changes,
modification time would stay the same.  But I do not know of a make like
tool which offers such model (possibly because normal filesystems do
not provide a way to store update time).

                              Waldek Hebisch

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