Configuring Subpackages

[Balint Joo]

Dear All,
        I have a (probably often heard) question.

My scenario is the following.

I have 3 packages. Let us call them A, B, and C.

A is installed somewhere with an A_config program that can tell
me various configurations options about A. Eg A_config --ldflags
can return as a string the LDFLAGS needed to link with A.

B is my main bundle

C is an extra library I distribute as a subdirectory of B and is optional.

I would like to use AC_CONFIG_SUBDIRS(C)
to configure C.

However, the autoconf script for C has various enable switches
that can be learned from the A_config script and are not really
relevant for B.

My problem is the following.

AC_CONFIG_SUBDIRS(C) will run configure with the same command line
switches as I ran configure with in B, but I want to turn on some
extra --enable switches for configuring in C.

Any ideas as to how to do this?

I currently try and set various environment variables in
the configure script for B. The env vars get their value from
A using A_config. I then export them, and then when performing
AC_CONFIG_SUBDIRS they pass on their values. So far so good.

The difficulty is when sometimes, during the post configure make,
configure is sometimes re-run just at the level of C, rather than
always in B -- some dependency tracking feature. In this case the environment 
variables made by B are not known as the configure for C is not run from
within the configure for B

There must be a simple solution to this. Sure I could use AC_CONFIG_COMMANDS
but that just seems wrong really.

Any better ideas?

        Balint

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Dr Balint Joo                         Post Doctoral Research Fellow
School of Physics
University of Edinburgh
Mayfield Road, Edinburgh EH9 3JZ
Scotland UK
Tel: 0131 650 6469 (from UK) +44-131-650-6469 (from outwith UK)
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email: address@hidden           address@hidden
WWW  : http://www.ph.ed.ac.uk/~bj
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