Functors in C++ are objects that behave like functions. They are used in various scenarios to provide a flexible and customizable way to perform operations. In this blog post, we will explore how to implement functors for custom memory deallocation in C++.

Memory deallocation is a critical aspect of programming, especially in low-level languages like C++. By default, C++ handles memory deallocation using the delete operator for single objects and delete[] for arrays. However, there may be scenarios where you need to perform custom memory deallocation, such as freeing resources or cleaning up memory in a non-standard way.

To implement a functor for custom memory deallocation, you’ll need to define a class that overloads the function call operator operator(). This allows the object to be invoked as if it were a function. In the case of memory deallocation, the operator() should free the allocated memory.

Here’s an example of how to implement a functor for custom memory deallocation in C++:

class CustomDeallocator {
public:
    void operator()(void* ptr) const {
        // Perform custom deallocation logic here
        // For example, freeing additional resources or cleaning up memory
        free(ptr);
    } 
};

In this example, we have defined a class called CustomDeallocator that overloads the operator(). The operator() takes a void* pointer as its argument, representing the memory location to deallocate.

Inside the function call operator, you can implement your custom memory deallocation logic. This could include freeing additional resources or cleaning up memory using a different method than the default delete operator.

To use the CustomDeallocator functor, you can pass an object of this class as an argument to a smart pointer class like std::unique_ptr or std::shared_ptr. These smart pointers take a custom deallocator object as a template argument, allowing you to control the memory deallocation process.

Here’s an example of how to use the CustomDeallocator functor with std::unique_ptr:

int* ptr = (int*)malloc(sizeof(int));
std::unique_ptr<int, CustomDeallocator> uniquePtr(ptr);

In this example, we allocate memory using malloc and assign it to a regular pointer ptr. We then create a std::unique_ptr using the custom deallocator CustomDeallocator.

When the std::unique_ptr goes out of scope or is explicitly deleted, the operator() of the CustomDeallocator object will be called to deallocate the memory.

By implementing functors for custom memory deallocation, you can have fine-grained control over the memory management process in C++. This is especially useful in scenarios where you need to perform additional cleanup operations or use a non-standard memory deallocation method.

#C++ #MemoryDeallocation