hi Akim, here is an example of what usage I have in mind:
I'd like to make a distribution for the 'Fresco' project. The code is a set of libraries, plugins, demos, etc., which are - for convenience - all to be configured / build with a single 'configure'. Among the components are some that are mandatory. If they can't be configured, nothing should be built. However, some components are optional. They can be loaded by the server at runtime (if present), but their absence doesn't prevent the whole from being useful. One such plugin is a 'SDL console'. Configuring this means to check for the presence of the 'SDL' library and headers. If that check fails, the 'SDL console' can't be built. But that's all there is about it, no need to abort the compilation. Your suggested test only covers the presence of the 'SDL console' sub-package in my distribution. But since I don't know whether a potential user has SDL installed on his system, I will put the 'SDL console' into my distribution and let configure figure out whether or not to compile it. I hope this illustrates the need for the requested feature... Thanks, Stefan