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Virtual

Virtual.member
marks a polymorphic member. Such nonprivate members are used relative to the class of an object. For other members within a method call, the method's class or its parents are scanned for the member, an object's class is irrelevant in this case. The opposite is Real.
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Basic Examples   (1)
This loads the package.
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The next example defines a simple set of classes.
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By default, fields are only searched for relative to the current calling context. The first access to a is relative to the object, while the second is relative to f that is a member of the base class.
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We now force polymorphism for nonprivate fields. The Override qualifier is used to emphasize that functionality of a parent class is changed. We must clear child before, because automatic regeneration of it during the redefinition of base is not consistent with the new base.
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Accordingly, the object's class determines where to search for a field.
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