Thank you for the reply—I read the thread you cited. I thought about how I would phrase the change to the doc, and interestingly I cannot think of what I would say that is both simple and true.
For example, it is not correct to say (as I did in the post for clarity) that tup must know how to make the file if it does not already exist. Because the file can exist and it would still be an error if it is “scheduled for deletion”. Further, there could very well be additional cases that I am not aware of. In my view, there seems to be no fundamental (mathematical or logical) reason for the rules to be required to be in a particular order. They are required to be in the order that the program expects them to be in, and I just do not know enough about how tup internals work to be able to describe its expectations. In my view, the biggest reason to make the rule order not matter (if that is indeed possible) is that it gets both the user and the documentation writer out of the business of describing these limitations on order (because there would be none). It is a powerfully good reason to have the rules be “declarative”, and in my view far more persuasive than the specific use case contemplated in the thread you cited. I acknowledge, however, that it might be impractical to make the rule order not matter, for reasons of code inertia or even related to performance. What I am suggesting, though, is that if it is practical to remove the hard-to-describe limitations, doing so would be really good. Thanks, Todd On Sun, Sep 8, 2019 at 2:36 AM Layus <[email protected]> wrote: > Yep, I also got bitten by this one :-). > > There is some discussion about this in the ill-named issue on github > https://github.com/gittup/tup/issues/247. > > Basically, it is not considered a pressing issue, and not really a bug. > > I guess a pull request on the doc would be trivial. Would you feel like > doing it ? > You can do it directly in github ( > https://github.com/gittup/tup/edit/master/tup.1) or send your updated/new > text here and I would happily make the PR. > > Regards, > > -- Layus. > > > On 8/09/19 01:50, Todd Doucet wrote: > > The documentation gives the following Tupfile in the section describing > how to handle a generated header file: > > : |> sh gen_triangle.sh > %o |> triangle.h > : foreach *.c | triangle.h |> gcc -Wall -c %f -o %o |> %B.o > : *.o |> gcc %f -o %o |> hello > > > That works fine in the example, but if you switch the order of the first > two lines, yielding: > > : foreach *.c | triangle.h |> gcc -Wall -c %f -o %o |> %B.o > : |> sh gen_triangle.sh > %o |> triangle.h > : *.o |> gcc %f -o %o |> hello > > > then tup generates an error on the first rule, saying that the file > triangle.h does not exist. Of course it does not exist, it is generated. > Apparently it needs to know how before it is willing to accept an > order-only dependency on that file. > > It took me a while to reduce the problems I was having to this, perhaps in > part because the documentation is silent on the order dependency. It is > odd that there is one and it took me a long time to realize this was the > problem. > > (In my case, I build an executable that in turn is run by a rule to > generate a header, which in turn is used to build the final executable. I > must have all three in the right order or it does not work. > > Perhaps a note about order dependency would be useful to others. Even > better, if possible simply make the rule order not relevant. > > -- > -- > tup-users mailing list > email: [email protected] > unsubscribe: [email protected] > options: http://groups.google.com/group/tup-users?hl=en > --- > You received this message because you are subscribed to the Google Groups > "tup-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/tup-users/2ea8d4ad-bb85-4ae7-8334-33d2439de175%40googlegroups.com > <https://groups.google.com/d/msgid/tup-users/2ea8d4ad-bb85-4ae7-8334-33d2439de175%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > > -- -- tup-users mailing list email: [email protected] unsubscribe: [email protected] options: http://groups.google.com/group/tup-users?hl=en --- You received this message because you are subscribed to the Google Groups "tup-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/tup-users/CACM4L_LegGYg7SDKq_DjL0Go_yFiE5gsMwbE0uCPoTnNWz08AA%40mail.gmail.com.
