Since these masks are unique to their class, not to different
instances, you could make sure that they were initialized properly by
making them static fields of the class with initializers.  This way,
they will be properly initialized before any of the steps in the
construction of a particular instance.

In general, the safest policy is to avoid calling non-static methods
from the constructor.  Therefore, the constructor cannot accidentally
call methods overridden by subclasses that aren't designed to be
executed before their own class's constructor has been run.
