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26 lines
1.6 KiB
Text
26 lines
1.6 KiB
Text
Classes having tt(pointer data members) have been discussed in detail in
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chapter ref(MEMORY). Classes defining pointer data-members deserve some
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special attention, as they usually require the definitions of copy
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constructors, overloaded assignment operators and destructors
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Situations exist where we do not need a pointer to an object but rather a
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i(pointer to members) of a class. Pointers to members can profitably be used
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to configure the behavior of objects of classes. Depending on which member a
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pointer to a member points to objects will show certain behavior.
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Although pointers to members have their use, polymorphism can frequently be
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used to realize comparable behavior. Consider a class having a member
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tt(process) performing one of a series of alternate behaviors. Instead of
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selecting the behavior of choice at object construction time the class could
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use the interface of some (abstract) base class, passing an object of some
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derived class to its constructor and could thus configure its behavior. This
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allows for easy, extensible and flexible configuration, but access to the
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class's data members would be less flexible and would possibly require the use
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of `friend' declarations. In such cases pointers to members may actually be
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preferred as this allows for (somewhat less flexible) configuration as well as
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direct access to a class's data members.
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So the choice apparently is between on the one hand ease of configuration and
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on the other hand ease of access to a class's data members. In this chapter
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we'll concentrate on pointers to members, investigating what these pointers
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have to offer.
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