Re: Automatically keeping "last modified" up to date

[Ethan A M. <sf...@us...>]

On Tuesday, August 06, 2013 12:26:04 pm Allin Cottrell wrote:
> On Tue, 6 Aug 2013, Ethan Merritt wrote:
> 
> > On Tuesday, August 06, 2013 10:25:33 am Daniel J Sebald wrote:
> >> I just built the most recent version of gnuplot and noticed that the
> >> "last modified" date in the intro refers back to 2012 and is manually
> >> entered.  Why can't that automatically be generated?  It would be nice
> >> to do this so that when one builds/installs the latest version, upon
> >> launching the program it is immediate clear that the install process was
> >> successful by looking at the "last modified" date.
> >>
> >> Here are some approaches that could be tried:
> >>
> >> 1) There is this configure.in file containing:
> >>
> >> dnl $Id: configure.in,v 1.332 2013/07/18 23:22:17 sfeam Exp $
> >>
> >> Is that file somehow generated by the CVS/repository to reflect the most
> >> recent modification of the repository?  If so, that would be great as it
> >> would also contain a time stamp.  Could write a script to search for
> >> that and define LAST_MODIFIED in some header file using the extracted
> >> "2013/07/18 23:22:17" string.
> >>
> >> 2) Is there some way during make to get the most recent date of all the
> >> pertinent files?  "make" does date checking, so perhaps there is a make
> >> variable/macro that reflects that.
> >>
> >> 3) Similar to #2, we could maybe write an OS script that does the same
> >> thing by looking for the date of the most recent file in the source tree.
> >>
> >> 4) Ethan keeps the ChangeLog up to date.  It would be easy to search for
> >> the most recent date near the top of the file and use that as a
> >> definition for LAST_MODIFIED.
> >
> > The file .../src/Makefile.maint exists for exactly this purpose.
> > It updates the version string based on the most recent date in ChangeLog.
> > This file is included during "make" by gnu make.
> > Possibly you are using some other make program?
> 
> I think there's something wrong with this. I definitely use 
> gnu make, but sometimes when I update from CVS, do prepare, 
> configure and make, I get a "last modified" date that is 
> (e.g.) 6 months ago and clearly wrong.

I believe you, but I don't know why this would happen.
I could imagine a state in which you had updated version.c once
in such a way that subsequent automatic updates failed.
This would leave the reported version stuck at some intermediate
date stamp, but it wouldn't be the one in the base CVS copy of the file.

> There's one other fishy thing in that neighborhood. When I do 
> a cvs update it seems I quite often get the cvs 'M' flag 
> indicating that src/version.c is modified, when I certainly 
> haven't edited that file.
> Allin Cottrell

Exactly.  That's as expected.
When you run "make" it changes gnuplot_date[] in version.c file to reflect
the most recently modified date.  So if you later update from CVS it sees
that your local copy of version.c is different from the base copy in CVS.

	Ethan