If you want to see why people give me a hard time: https://github.com/kubernetes/kubernetes/blob/master/build/root/Makefile.generated_files
And that's AFTER a massive simplification. On Mon, Jan 28, 2019 at 11:55 AM Ian Lance Taylor <i...@golang.org> wrote: > > On Mon, Jan 28, 2019 at 11:44 AM Tim Hockin <thoc...@google.com> wrote: > > > > Of course you are right, as usual. I just felt like that was a lot of > > hoop-jumping. People already chide me for my affinity for baroque > > Makefiles... > > If you can assume that you are using GNU make, the Makefile language > is Turing complete (although some limits are applied to rule expansion > so you can't write an infinite loop). > > Ian > > > > On Sat, Jan 26, 2019 at 11:01 AM Ian Lance Taylor <i...@golang.org> wrote: > > > > > > On Fri, Jan 25, 2019 at 7:55 PM Tim Hockin <thoc...@google.com> wrote: > > > > > > > > Fair point, of course. > > > > > > > > I care because Kubernetes and it's family of projects have Makefiles to > > > > encapsulate trickier aspects of building, including code generation. > > > > Compiling kubernetes takes a LONG time. It would be nice to avoid > > > > re-triggering secondary actions when the primary artifacts have not > > > > changed. > > > > > > > > Could I checksum? Sure, but then I am writing a custom builder, so I > > > > might as well use Bazel (which has other issues). > > > > > > > > It's not a huge deal, today, but I really wanted to understand it. It > > > > just seemed broken. > > > > > > While understanding that the approach is second best, Makefiles are > > > fully able to handle files that have the same contents but updated > > > timestamps. You separate the file you create and the file you use. > > > Then you write a Makefile target like > > > > > > progtouse: stmp-progtouse; @true # Yes, the "; @true" is important. > > > stmp-progtouse: dependencies to build progtobuild > > > # commands to build progtobuild > > > $(SHELL) mvifdiff.sh progtobuild progtouse > > > echo >$@ > > > > > > The shell script mvifdiff.sh is simply > > > > > > if cmp -s "$1" "$2" ; then > > > rm -f -- "$1" > > > else > > > mv -f -- "$1" "$2" > > > fi > > > > > > Then everything else depends on, and uses, progtouse. > > > > > > Remember to remove stmp-progtouse in your clean targets. > > > > > > Ian -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
