How Can I Overwrite Global `new` and `delete` Operators Without Modifying Existing Code?

Overwriting Global new and delete Operators

The intricacies of overloading global new and delete operators can be daunting, particularly when dealing with a complex code base and third-party libraries. However, a simple and effective approach exists that eliminates the need for widespread header file inclusion.

As stated by the expert, all that is required is to define these operators in a separate translation unit (TU) and link it to the project. This TU can be a straightforward implementation, as demonstrated below:

<code class="cpp">// optional_ops.cpp

void * operator new(std::size_t n) throw(std::bad_alloc)
{
  //...
  // Your custom memory allocation implementation
}

void operator delete(void * p) throw()
{
  //...
  // Your custom memory deallocation implementation
}</code>

To avoid potential errors, it is advisable to include necessary headers to declare names such as std, std::bad_alloc, and std::size_t. This ensures that your overloads can seamlessly integrate with the existing code base.

In later versions of C (C 11 onwards), an alternative approach can be employed:

<code class="cpp">void * operator new(decltype(sizeof(0)) n) noexcept(false)
{
  //...
}</code>

This method eliminates the need for external headers and provides a cleaner and more concise implementation.

By adopting this approach, the custom memory manager can be globally enforced without requiring extensive code modifications or header file dissemination. It is a clean and efficient solution to manage memory operations throughout the application, ensuring consistent memory allocation and deallocation behavior.

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