Clause 52: Thanks placement new also should write a placement delete

If operator new receives parameters other than size_t, then this operator new is actually a placement new, so consider the following scenario:

A placement new that can be used to record information:

1 classwidget{2  Public:3     ...4     Static void*operator New(std::size_t size, std::ostream & logstream =std::cout)5         Throw(std::bad_alloc);6     Static void*operator Delete(void* Pmem, std::size_t size)Throw();7     ...8};

So when we create a new widget:

1 New (Std::cerr) Widgets;

At this point, if the new is successful but fails to construct the widget, then the system cannot find the corresponding delete to release the allocated raw memory, which will cause a memory leak. So when providing placement new, be sure to provide the corresponding placement delete so that no memory leaks occur. Placement Delete is as follows:

1 Static void operator Delete (void * pmem, std::ostream& logstream);

The simple form of completing all the points is to create a base class that contains all the normal forms of new and delete. The simple form of completing all the points is to create a base class, Contains all the normal forms of new and delete. The simple form of completing all the points is to create a base class that contains all the normal forms of new and delete.

1 classstandardnewdeleteforms{2  Public:3     //Normal New/delete4     Static void*operator New(std::size_t size)Throw(Std::bad_alloc)5     {6         return::operator New(size);//The Global new is used here.7     }8     Static void operator Delete(void* Pmem)Throw()9     {Ten         return::operator Delete(PMEM); One     } A     //Placement New/delete -     Static void*operator New(std::size_t size,void* ptr)Throw() -     { the         return::operator New(size, ptr); -     } -     Static void operator Delete(void* Pmem,void* ptr)Throw() -     { +         return::operator Delete(Pmem, PTR); -     } +     //nothrow New/delete A     Static void*operator New(std::size_t size,ConstStd::nothrow_t & NT)Throw() at{return::operator New(size, NT);} -     Static void operator Delete(void* Pmem,ConstStd::nothrow_t & NT)Throw() -{return::operator Delete(Pmem, NT)} -};

You can then use both inheritance and the using declaration to get the new and delete you want:

1 classWidgets: Publicstandardnewdeleteforms{2  Public:3     usingStandardnewdeleteforms::operator New;4     usingStandardnewdeleteforms::operator Delete;//introduce them to the scope so that the global new and delete are obscured. 5     Static void*operator New(std::size_t size,6Std::ostream & LogStream)Throw(std::bad_alloc);7     Static void*operator Delete(void*Pmem,8Std::ostream & LogStream)Throw();9};

Clause 52: Thanks placement new also should write a placement delete