You could surely come up with a scheme of that kind in your application. To make it as simple as possible, you could simply have a global variable with the allo

You could surely come up with a scheme of that kind in your application. To make it as simple as possible, you could simply have a global variable with the allocator you want to use, and pass a reference to it to every stdlib function you use; nothing stops you from doing that. The explicitness is supposed to be respected by libraries, so that then the writer of the final program can enjoy maximum flexibility.