Re: Linking to external libraries. Possible FAQ.

From: David Abrahams (dave_at_[hidden])
Date: 2002-11-29 17:58:24

"Jørn Jensen" <jornj_at_[hidden]> writes:

> Hello Dave,
>
> I sent a question like this to the jamboost archive which I subscribe too.
> But I never got any replies and thought I was ignored for asking stupid
> questions. So I gave up on the whole issue for a while, until I saw the
> light today when I understood how <linkflags>, <library-path> and
> <find-library> actually work. They modify variables..
>
> Then, an hour later, I scan some google searches and find that you answered
> on my original question (me aka jornj2001_at_[hidden]). I never got that mail,
> and I have not been able to trace it in my quite big mail log.

I don't know why this didn't go to the Jamboost list, but since it
seems to be entirely devoid of nontechnical content I don't see a
reason not to copy it there...

> I wrote:
>>> My apologies if this is obvious, but I suspect there is a bug in the
>>> current jamboost, boost_1_29_0, on linux with gcc. Or with the
>>> documentation that specifies that I should use LINKLIBS.
>>
>> Which documentation tells you to do that?
>
> I have not been able to find the documentation that referred to
> LINKLIBS. And at this point I can't remember any of it. :-( I have
> a lot of links in my bookmark list with references to mail archives
> for Jam/MR, various Jambases and Boost Build System. Sorry about
> that. At the time I wrote it, I obviously thought I had seen a
> reference to it somewhere. And now I am unable to find
> it. Embarassing, but I cannot find it anymore.

Maybe in the regular Jam/MR Jambase documentation. Anyway, Boost.Build
basically doesn't use any of the Jambase idioms.

> Anyway, thank you for your answer, I only wish it had somehow reached me
> earlier. Heh.
>
> My problem when reading the BJam documentation on the net is that I
> know how to do it with 'make', and I had a hard time understanding
> 'how to accomplish X' in Jam. Some of the documentation is more
> list-oriented than problem-oriented. Features are listed, but not
> how to solve problems, which was my angle. Of course, it could be
> that I was half blind by previous misconceptions of 'how things
> worked'. The differences between Jam and BJam (different rule names
> etc.) was also quite confusing. The examples that are provided are
> all quite straight forward, assuming you have all your files within
> the same build system and in a relatively sane directory structure.
> Unfortunately, I don't :-)
>
> What I like about BJam is that it is very easy to specify how to
> build a library or a dll and get all the platform specific out. I
> also like the optimistic dependency system that doesn't break if the
> header file is gone.
>
> I have been able to convert one of my bigger Makefiles into a
> Jamfile, and it looks good. I have not modified any of the Jambase
> files and have added no new rules to accomplish it. This is good.
>
> My three next quests are:
>
> * Figuring out how I can make the existing make (we have a pretty
> big system here) can be made to interface with files made with
> bjam. This probably involves installing the files into a location
> that can be reached by our existing system without too much grist. I
> read one mailing that directed the questioner to have a look at the
> stage keyword.
>
> * Experiment more with the 'run' rule in testing.jam and figure out
> why I cannot specify something like this:
>
> run FooTest.cpp <dll>Foo. So far I have not been able to make the
> FooTest.test target link with the libFoo.so at all, it is just
> ignored.

Yeah, we seem to be having the same problem in the Boost.Python
embedding test. I've asked Rene, who's been maintaining this part of
Boost.Build v1, to look at it.

> * Somehow justify the time I have spent figuring this out. :-)

Gee, sorry ;-(

If you want to make it better, you could contribute a Wiki page on
Boost.Build.

You might look here:

http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?CommonBuildProblems

and/or here:

http://www.python.org/cgi-bin/moinmoin/boost_2epython_2fBuildingExtensions

-- 
David Abrahams
dave_at_[hidden] * http://www.boost-consulting.com
Boost support, enhancements, training, and commercial distribution