Effective C++ 52. Write placement delete if you write placement new

I.
if memory allocation succeeds and the Widget constructor throws an exception, the runtime system is responsible for undoing the allocation that operator new performed. The runtime system looks for a version of operator delete that takes the same number and types of extra arguments as operator new.

class Widget {public:    static void* operator new(std::size_t size, std::ostream& logStream) throw(std::bad_alloc);    static void operator deleted(void* pMemory) throw();    static void operator deleted(void* pMemory, std::ostream& logStream) throw();};Widget *pw =  new(std::cerr)Widget; // no leak // if no exception is thrown, the normal operator delete is invokeddelet pw; // invokes the normal operator delete

II.
Operator news in derived classes hide both global and inherited versions of operator new
C++ offers the following forms of operator new at global scope

void* operator new(std::size_t) throw(std::bad_alloc);void* operator new(std::size_t, void*) throw();void* operator new(std::size_t, const std::nothrow_t&) throw();

calss StandardNewDeletForms {public:    // normal new/delete    static void* operator new(std::size_t size) throw(std::bad_alloc) {         return ::operator new(size);     }    static void operator delete(void *pMemory) throw() {        ::operator delete(pMemory);    }    // placement new/delete    static void* operator new(std::size_t size, void* ptr) throw() {        return ::opertator new(size, ptr);     }    static void operator delete(void* pMemory, void* ptr) throw() {        return ::operator delete(pMemory, ptr);    }    // nothrow new/delet    static void* operator new(std::size_t size, const std::nothrow_t& nt) throw() {        return ::operator new(size, nt);    }    static void operator delete(void* pMemory,const std::nothrow_t&) throw() {        ::operator delete(pMemory);    }};class Widget: public StandardNewDeleteForms {public:    using StandardNewDeleteForms::operator new;    using StandardNewDeleteForms::operator delete;    static void* operator new(std::size_t size, std::ostream& logStream) throw(std::bad_alloc);    static void operator delete(void *pMemory, ostream& logStream) throw();};