Re: GNU make to consider files checksum

[Paul Smith]

On Thu, 2008-08-28 at 09:06 +0200, Giuseppe Scrivano wrote:
> I sent a message to this mailing list some months ago but I still
> didn't get an answer.  Doesn't GNU Make want to consider files
> checksum in addition to mtime?

There was a Google SOC project for GNU make which added "user-definable
out of date" criteria; these could be defined on a per-target basis and,
as per the name, were defined by the user, not hardcoded (as md5sum
would be).  For example, you can short-circuit an expensive md5sum check
by simply comparing the file sizes: most of the time they will be
different and if so you can skip md5sum altogether.

The major change this implies is that you must have a "stateful make"; a
make that stores state from previous invocations, then reads it the next
time.  Normal make is stateless; or at least it uses only the state
provided by the filesystem and not its own state.


The project was successful in that the changes were delivered; however,
the user interface implementation is, in my opinion, too baroque at the
moment.  Its use model confuses me, anyway.  This is not so much the
fault of the student as my fault: I simply did not have enough time to
be a good mentor for the project and provide enough direction.  I knew
this would be an issue (I didn't solicit anyone to do this work but
someone contacted me and really wanted to do it, and I wanted it done)
but I hoped I would find the time.  And, a lot of really good work was
done... it's just the presentation to the user that I think needs more
effort.

-- 
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 Paul D. Smith <address@hidden>          Find some GNU make tips at:
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 "Please remain calm...I may be mad, but I am a professional." --Mad Scientist