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cs31 lecture 15

X we have a class b a x we have we b b a a b b x iin

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Unformatted text preview: does it work? x We have a class B : A x We have We B b; A a = b; b; x IIn A, we have a virtual method foo(), and in B we have reimplemented n a method foo() method x Without dynamic dispatch, a.foo() is the implemementation in A x With dynamic dispatch, a.foo() is either A::foo() or B::foo(), With depending on what a is storing depending No dynamic dispatch: A a = A(); With dynamic dispatch: A* a = new B(); // or new A(); 6 Examples 7 Pointers versus references x In C++, one key reason of constructors/destructors is In when pointers are used as attribute when x References give you less freedom than pointers x Pointers are more error-prone than references x std::vector<A&> is not possible, but std::vector<A*> is std::vector<A&> possible possible 8 A new data structure: trees x A tree is made of nodes, which have a unique parent, and tree possibly many children possibly x A good example: a document tree (a HTML page) x Design: Design: Each node is a Node class Each particular node type inherits from Node Each particular node has its own print function We can make vector of Node We Printing a document is about traversing the tree, and calling the Printing actual print method of each node actual 9...
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