How to Universally Override Global `new` and `delete` Operators in Large Codebases?

Overriding Global New & Delete Operators Effectively

Problem:

Replacing the global new and delete operators to use custom memory management presents challenges in large-scale codebases. Including the header file containing the overloads in every file is impractical. How can one ensure universal adoption of these overloads?

Solution:

Overriding new and delete operators is a process done at link time. By creating a separate translation unit (TU) that defines the operators and linking it into the project, one can replace the default operators globally without modifying the existing codebase.

Code Sample:

Here is an example of a TU defining the new and delete operators:

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

void * operator new(std::size_t n) throw(std::bad_alloc)
{
  //...
}

void operator delete(void * p) throw()
{
  //...
}</code>

Including the header is not required as the declarations for operator new and operator delete are hardcoded into the language. However, names such as std, std::bad_alloc, and std::size_t may need to be declared.

Alternative for C 11 and Later:

C 11 introduces a simpler way to define the new overload, using decltype(sizeof(0)) to determine the type of the size parameter:

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

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