Item 51: Adhere to Convention When Writing new and delete

Here are the conventions (tricker than you thought):

To write a conformant operator new at least you have to:

• Return the right value (duh!)
• Call thew new-handler function when space unavailable
• Cope when no memory
• Avoid hiding the “normal” new
• Return a legitimate pointer even when the requested size is zero

To write a confromant operator delete at least you have to:

• Always safe to delete null pointer

Note:

• operator new will be inherited be derived classes - which might not be what you want (especially when you are optimizing the allocator for one, fixed size)
• You cannot assume the size parameter passed to operator new[] equals to sizeof(Base) * num_elements because:
  • It could be called from derived class
  • There could be extra space for recording the number of elements