This is the first of several large commits changing several aspects of
the handling of defaults. The overall main purpose of these changes is
to protect against using non sensible values in the case the values have
not been sensibly specified in the deck. The changes in this commit
include:
1. The "default default" values to be used when an item without an
explicit default are defaulted are removed completely.
2. If a ParserItem is queried for a default value when no default has
been assigned it will raise an exception.
equals(ParserIntItem&) has a different signature than equals(ParserItem&),
thus the former method does *not* overload the latter. Virtual just means
then only means that you have created a *new* entry in the v-table. If
you call equals through a pointer/reference to the base class ParserItem,
the defined method in the derived class is not called, and we miss out the
test for the equal default value.
Instead, we should take an argument of the base type and use a dynamic
cast to the derived type. If this downcast fails, then they are not equal;
otherwise we have gotten ourselves a pointer to get the properly typed
default value.
We must use pointers instead of references; if we cast to a reference,
a bad_cast exception is thrown if the expression is not in the proper
type hierarchy.
