206 ◾ Software Essentials
Additionally, as shown in Example 7.16, the AbsoluteVariable class
redenes the inherited NOP set functions as pure virtual, forcing descen-
dant classes to dene their own set functions. Why? Descendant classes
gain enough type information to implement set methods. For utility, child
classes of the AbsoluteVariable class must provide a set function to
identify the result of type interpretation.
As shown in Example 7.17, those descendant classes that dene Clone()
are no longer abstract. Not until the type of variable or constant is known
can the derived class provide an implementation for Clone(). Why? Data
cannot be copied without size information! e disassembler code can
instantiate objects from this tier of ...