Re: question about handling dependent libraries...

[Ralf Corsepius]

On Thu, 2006-03-16 at 12:48 -0700, Ed Hartnett wrote:
> All,
> 
> If I have a library (netcdf) which depends on another library (hdf5),
> which, in turn, may use another library (zlib), is there a good way to
> package things for the end user?
> 
> At the moment, my end user must first install zlib. Then they must
> build HDF5 with a --with-zlib=/somewhere argument, and then install
> HDF5. Then they will build netCDF with a --with-hdf5=/somewhere
> argument.
> 
> This is all working now, but it's a big burden for the user.
>
> Should I make a tarball which includes and installs all three in a
> single step? This is one thing I am considering. (Using the
> AC_CONFIG_SUBDIRS macro). 
I advocate against this practice. Experience tells, it's more confusing
and error-prone than not doing so.

Tell your users how to configure the package correctly.

I'd even not use --with-zlib/--with-hdf5, but tell them to use
CPPFLAGS, etc.

> However, how to handle cases where one of these is already installed
> on the end-user system?
If you really want it, check for the libs and header, and then only
enter the config-subdirs if you found you need to.

AS_IF([test $zlib_available],[
AC_CONFIG_SUBDIR([zlib])])

And 
SUBDIRS = @subdirs@
(Or a custom magic to setup SUBDIRS)
in Makefile.am should work.

> Anyone autotool-using library builder out there who has tried this?
It's pretty common, but as I've said, ... I would not recommend doing so.

> Any comments on this sort of problem, and solutions for it, would be
> very helpful. 
I recommend to try to "KISS", i.e. as little magic as possible.

Simply stay with AC_CHECK_HEADERS, AC_CHECK_LIBS etc. and let your
configure script error out/complain if something can't be found.

Ralf