This at least slightly improves the old design. In that design the
subclass had no own constructor but inherited the one of the base class.
That base class constructor called certain subclass
functions (createGrids_, filterConnections_, updateOutputDir_, and
finalizeInit_)that would initialize raw pointers of the
subclass. Hence subclasses where not allowed to have non-pod members
and those used later (e.g. deleted in the destructor) had to be
initialized in these functions.
The new (still ugly) design introduces constructors into the
subclasses and skips inheriting constructors. Now one must call a base
class function classImplementationInit which will still call the
functions createGrids_, filterConnections_, updateOutputDir_, and
finalizeInit_, but at least at this point the baseclass is fully
constructed and the subclass is constructed as much as
possible/needed (non-pod types will be initialized now.)
IMO the term "vanguard" expresses better what these classes are
supposed to do: level the ground for the cavalry. Normally this simply
means to create and distribute a grid object, but it can become quite
a bit more complicated, as exemplified by the vanguard classes of
ebos..
