ado@bbn.com (Buz Owen) (04/02/91)
The following program is illegal in C++: class B { int i; int j; public: operator = (int); } class D : public B { } main() { D d; d = 1; // error } because the assignment operator is not inherited by a subclass. I submit that this constraint can be usefully relaxed to apply only to any of the four operators: B::operator = ( [const] B [&] ) If the constraint were relaxed as I suggest, and a class B defined operator = members other than one of the above, they would be inherited by subclasses of B. The compiler would still compose the subclass assignment opeator(s) according to the present rules, using the automatically generated or explicitly defined base class assignment operators (one of the 4 above) to copy the base class members, and then performing memberwise assignment of members unique to the derived class. As an example in which overloading assignment to accept rhs arguments of other than the class type might be useful, consider a Timer base class in which assignment is overloaded to set the timeout value of the timer, with the side effect of starting the timer running. Buz Owen BBN Systems and Technologies Cambridge, Mass. ado@bbn.com