Re: Automatically keeping "last modified" up to date

[sfeam (E. Merritt) <eam...@gm...>]

On Wednesday, 07 August 2013, Hans-Bernhard Bröker wrote:
> On 07.08.2013 10:53, Lars Hecking wrote:
> >   I'm wondering if the best option is to put all the changeable items into
> >   a generated header file that is included by version.c; even config.h would
> >   do.
> 
> That approach would have its own downsides.  The first that comes to 
> mind is that there are builds of gnuplot that do _not_ use autotools, 
> thus no (automaticallly updated) config.h either.  Right now, only one 
> of those (config/mingw/Makefile) tries to duplicate the effect of 
> modifying version.c on-the-fly.  The others only get that effect if 
> either autotools or the MinGW makefile did the modification already.
> 
> Generally, any extra file this information would go into will be missing 
> completely in non-autotools builds.
> 
> And if you put that stuff into the main config.h, that that would defeat 
> the purpose of make, because every time you update ChangeLog, the entire 
> program would be rebuilt.  That can't be right.

How about changing version.c to something like

#ifndef LAST_MODIFIED
#define LAST_MODIFIED "2012-06-19"
#endif
const char gnuplot_date[] = LAST_MODIFIED;

And then using some autotools magic that I would have to hunt for
do something along the lines of

LAST_MODIFIED = <some magic involving awk or grep>
DEFS = $DEFS -DLAST_MODIFIED=${LAST_MODIFIED}

That should reproduce the current behavior without modifying
any source files. 

	Ethan
	
> 
> As far as I'm concerned, I haven't seen that mechanism actually working 
> for so long I didn't even know it existed before this discussion.  I run 
> builds using multiple compilers, and the out-of-tree builds that 
> requires break the version.c update mechanism.
> 
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