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POOverriding operator new/delete in derived class
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copied!<p>I have a stateless, abstract base class from which various concrete classes inherit. Some of these derived classes are stateless as well. Because many of them are created during a run, I'd like to save memory and overhead by having all stateless derived classes emulate a singleton, by overriding operator new()/delete(). A simplified example would look something like this:</p> <pre><code>#include <memory> struct Base { virtual ~Base() {} protected: Base() {} // prevent concrete Base objects }; struct D1 : public Base { // stateful object--default behavior int dummy; }; struct D2 : public Base { // stateless object--don't allocate memory void* operator new(size_t size) { static D2 d2; return &d2; } void operator delete(void *p) {} }; int main() { Base* p1 = new D1(); Base* p2 = new D1(); Base* s1 = new D2(); Base* s2 = new D2(); delete p1; delete p2; delete s1; delete s2; return 0; } </code></pre> <p>This example doesn't work: <code>delete s2;</code> fails because <code>delete s1;</code> called <code>~Base()</code>, which deallocated the shared <code>Base</code> in <code>d2</code>. This can be addressed by adding the same trick with new/delete overloading to Base. But I'm not sure this is the cleanest solution, or even a correct one (valgrind doesn't complain, FWIW). I'd appreciate advice or critique.</p> <p>edit: actually, the situation is worse. The Base class in this example isn't abstract, as I claimed. If it's made abstract, through the addition of a pure virtual method, then I can no longer apply the new/delete overriding trick, because I cannot have a static variable of type Base. So I don't have any solution for this problem!</p>

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