Re: Future of C++
On Aug 7, 8:58 am, Razvan Cojocaru <razva...@gmx.net> wrote:
[Restoring attribution]
Eugene wrote:
Nonsense. First of all there is nothing wrong with having a non-
virtual *protected* destructor in a base class. Second introducing
such change will immediately break every Windows COM component ever
written.
Is it? How does a protected base class destructor solve the following
problem?
class Base {
public:
virtual perform() = 0;
protected:
~Base() {} // non-virtual destructor
};
class Derived : public Base {
[snip]
};
int main()
{
std::auto_ptr<Base> pb(new Derived);
[snip]
This shouldn't compile since std::auto_ptr<Base> cannot call Base dtor
(via delete operator).
Unlike Java, 'protected' in C++ only gives access to derived classes.
Theoretically, you *can* construct pathological code where Derived
tries to destroy an instance of *itself* via Base destructor. However,
I doubt you'll ever find such code in practice.
As for messing all COM+ legacy code up, I'm not a COM+ expert but I
don't see why that would be the case.
Because COM relies on virtual table layout to achieve binary
interoperability between code written by different people in different
languages. If you silently change vtable layout of existing code it
will fail to talk to code built with an earlier compiler.
--
Eugene
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