[CMake] more targets to run in parallel

[Andrea Crotti]

So suppose I have a list of Python eggs, in the form.

- egg1
- egg2
- ..

What I would like to do is to have be able to do.
cmake .
make build_eggs

which would go over the list of the eggs and run in each of them

python setup.py bdist_egg -d <some_path>

The list of eggs is actually computed at run-time, so I created a custom
command and a custom target:

add_custom_command(OUTPUT ${INSTALLED_EGGS_LIST}
   COMMAND "${PYTHON_EXECUTABLE} ${GEN_DEPENDENCY_SCRIPT} 
${BUILD_APP_OPTIONS}"
)

add_custom_target(generate_dependency_file
   DEPENDS ${INSTALLED_EGGS_LIST}

)

So now, is there a way to create one target for *each* egg in the list?
And then I also need also a way to have another target that actually
depends on all these other targets, is that possible?

I could have just one target to build them all, but then it would not be
able to actually run in parallel (with make -j), is that correct?