how to let configure know include and library path for library foo?

[Sébastien Hinderer]

Dear all,

When an autoconf-driven project has a dependency on library foo, what's the
best / recommended way to let users specify the directories for header
files and library files when configuring the project?

For the XWindow system, for instance, there are the --x-includes=DIR
and --x-libraries=DIR options, and also --with-x to enable / disable X.

I assume it's good to also provide three options for each library: one
to let configure know whether it should be enabled or not, i.e. an
equivalent of --with-x, and two options to specify the header and
library directories. But, of course, it is not possible to define
--foo-includes=DIR and --foo-libraries=DIR as is done for X, so is one
supposed to use AC_ARG_VAR to achieve this?

Many thanks in advance for your recommendations,

Sébastien.