8.2 Building a library

Building a library is much like building a program. In this case, the name of the primary is ‘LIBRARIES’. Libraries can be installed in libdir or pkglibdir.

See Building a Shared Library, for information on how to build shared libraries using libtool and the ‘LTLIBRARIES’ primary.

Each ‘_LIBRARIES’ variable is a list of the libraries to be built. For instance to create a library named libcpio.a, but not install it, you would write:

noinst_LIBRARIES = libcpio.a

The sources that go into a library are determined exactly as they are for programs, via the ‘_SOURCES’ variables. Note that the library name is canonicalized (see How derived variables are named), so the ‘_SOURCES’ variable corresponding to liblob.a is ‘liblob_a_SOURCES’, not ‘liblob.a_SOURCES’.

Extra objects can be added to a library using the ‘library_LIBADD’ variable. This should be used for objects determined by configure. Again from cpio:

libcpio_a_LIBADD = $(LIBOBJS) $(ALLOCA)

In addition, sources for extra objects that will not exist until configure-time must be added to the BUILT_SOURCES variable (see Built sources).

Building a static library is done by compiling all object files, then by invoking $(AR) $(ARFLAGS) followed by the name of the library and the list of objects, and finally by calling $(RANLIB) on that library. You should call AC_PROG_RANLIB from your configure.ac to define RANLIB (Automake will complain otherwise). AR and ARFLAGS default to ar and cru respectively; you can override these two variables my setting them in your Makefile.am, by AC_SUBSTing them from your configure.ac, or by defining a per-library maude_AR variable (see Program and Library Variables).