Objects that stand for other objects are called proxy objects or surrogates.
template <class t="">
class Array2D
{
public:
class Array1D
{
public:
T& operator[] (int index);
const T& operator[] (int index)const;
};
Array1D operator[] (int index);
const Array1D operator[] (int index) const;
};
The following then becomes legal:
Array2D<float>data(10,20);
cout<<data[3][6]; // fine
Here data[3] yields an Array1D object and the operator [] invocation on that object yields the float in position(3,6) of the original two dimensional array.
Clients of the Array2D class need not be aware of the presence of the Array1D class. Objects of this latter class stand for one-dimensional array objects
that, conceptually, do not exist for clients of Array2D. Such clients program as if they were using real, live, two-dimensional arrays. Each Array1D object
stands for a one-dimensional array that is absent from a conceptual model used by the clients of Array2D. In the above example, Array1D is a proxy class. Its
instances stand for one-dimensional arrays that, conceptually, do not exist.
Name some pure object oriented languages.
Smalltalk, Java, Eiffel, Sather.
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