Project inheritance/extension, being allowed to set $basedir would be helpful

[Colin Sampaleanu <co...@exis.com>]

Generally, subprojects which inherit from a parent project do not work 
with the same directories and artifacts that the parent project does.

There is however a case where this would be very useful, and for this to 
be easy to do, the subproject needs to think it has a different $basedir 
than the one the project.xml file is in (although the maven.xml and 
project.properties alongside it should still be read).

Consider the 'ear' plugin. It can currently only build an ear file with 
artifacts which are already in the remote or local repository (as a 
result of an 'install'). However, it would be much more useful if you 
could have a project which compiled code, built jars and wars, and then 
built the ear. One way to handle this would be to have a project build 
up all the artifacts and install them, then call (via the reactor) a 
subproject to create the ear file. The important thing is that if the 
subproject thought it's basedir was the basedir of the parent project, 
then it could reuse all the src artifacts relative to the parent. 
Otherwise, any reference to a file (via a property) needs to be 
overriden in the child project (consider for example the property which 
points to the standard location for the application.xml file, for which 
there is a default value in the plugin, or the manifest, etc. Without 
being able to override the basedir, these artifacts have to be found 
either by overriding all the default properties, or else by actually 
placing them in the subproject.

Thoughts?

Colin