FAQ 10.4: How do I build a DLL using Cons?

[Vaclav Barta]

Hi,

I finally got to writing it down, but of course I've made some little
changes in the process, and I can't check the final
version because I don't have access to Visual C++ any more... So
(as always) use at your own risk, and I don't think 
the instructions should go into the FAQ until somebody tries to follow
them...

        Bye
                Vasek

10.4. How do I build a DLL using Cons?

You can build a DLL with a Library command, but the command requires some custom variable settings in its construction environment, primarily how to compile:

        CXXCOM => "%CC %CXXFLAGS %_IFLAGS /TP /c %< /Fo%>"
    (note that this is for a C++ project; straight C compilation
    would use CCCOM) and how to link:
        ARCOM => "%CC %CXXFLAGS %_IFLAGS /LD /Fe%>:b %<"
    (note the :b suffix; the Microsoft linker is usually passed
    the full name - including the .dll extension - but seems
    equally happy without it, and cons is much happier that
    way).

The compiler switches in the commands above are for Visual C++ - see its documentation for their description (and if you're using another C/C++ compiler, note that it'll very probably have the same functionality, but with a different syntax). You'll also need to specify (at least) CPPPATH (see FAQ 6.6), CXXFLAGS (see below) and ENV. With an environment like that, simply putting

        Library $env "#output\\package1", qw(modulea.cc moduleb.cc);
    into your Conscript file (in, say, package1
    directory) will build package1.dll (in
    output directory) from modulea.cc and
    moduleb.cc.

Note that the example above does not have separate debug vs. release builds (although it can be extended for that - see also FAQ 7.4), Windows resources (I did not try those) and does not use the .def file. The last choice means that __declspec(dllexport) must be used when declaring functions exported from package1.dll in package1 (and __declspec(dllimport) when declaring them in the DLL's clients); the preprocessor directive controlling the linkage specification (say, /DPACKAGE1DLL) goes to CXXFLAGS.