Re: C++ operator overloading q.

On Feb 8, 10:57 am, suresh shenoy <msureshshe...@gmail.com> wrote:

#include <iostream>

using namespace std;

class CategoryStream;

/*
  cspf is the name of a type. That type is a function pointer. That
type
  can point to any function that takes a reference to CategoryStream
and
  returns a reference CategoryStream.

  Note: It is highly likely that the function returns the parameter
that it
  takes.
*/
typedef CategoryStream& (*cspf) (CategoryStream&);

/*
  This function can be pointed to by a cspf, because it takes a
reference
  to CategoryStream, and returns a reference to a CategoryStream:
*/
CategoryStream & foo(CategoryStream & param)
{
    /*
      Normally, this function is expected to do something to param.
This is
      similar to sending hex to cout as in

          cout << hex;
     */
    cout << "in foo\n";
    return param;

}

class CategoryStream
{
public:

    CategoryStream & operator<< (cspf);

};

// Here is how one might use foo:
void bar()
{
    CategoryStream stream;

    // ignoring the return value here
    foo(stream);

}

CategoryStream& CategoryStream::operator<< (cspf pf)
{
    cout << "in operator<<\n";
    return (*pf)(*this);

}

int main()
{
    CategoryStream stream;
    stream << foo;

    /*
      Because operator<< returns a reference to CategoryStream, we c=

      cascade any number of those:
    */
    stream << foo << foo;

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