Q:

What are the serious uses of returning the this pointer from a function?

Following is a fancy code:
class B
{
    private:
        int sum;

    public:
        B ()
        {
            sum = 0;
        }

        B& add (int number)
        {
            sum =+ number;
            return *this;
        }
};

int main ()
{
    B obj;
    obj.add (1).add (2).add (3). add (4);
}

Fine, what are the "serious" uses of returning the this pointer from a function call?

A:

An example would be;
class basic_ostream
    : ...
{
    basic_ostream& operator<<(bool n);

You really want to return this to be able to chain to;
std::cout << boolValue << std::endl;

