Fixed length memory pool

Write a fixed length memory pool !

#pragma once
#include <iostream>
using std::cout;
using std::endl;

//  Fixed length memory pool !
// template<size_t N>
// class ObjectPool {};

/*  The left value   and   Right value   The left value  :  stay  '=' Sinister , In fact, the memory contents of variables should be overwritten !  Right value  :  stay  '='  Dexter , In fact, the contents of the memory where the variable is located should be taken out ! */
template<class T>
class ObjectPool {
    

public:
	T* New() {
    
		T* obj = nullptr;
		if (_freeList) {
    //  The memory released is still there !  Delete the header !
			void* next = *(void**)_freeList; //  The contents of the pointer are given to next The pointer 
			obj = _freeList;
			freeList = next;
			new (obj)T;
			return obj;
		}
		if (residualSize < sizeof(T)) {
     //  There is not enough memory left !
			residualSize = 128 * 1024;
			_memory = malloc(residualSize); //  Apply for another piece !
			if (_memory == nullptr) {
     //  Memory request failed !
				throw std::bad_alloc(); //  Throw exceptions , To terminate the program !
			}
		}

		obj = (T*)_memory; //  Cut a piece of memory for him !

		//  Ensure that the requested memory can be organized in the form of a linked list !
		size_t obj_size = sizeof(T) > sizeof(void*) ? sizeof(T) : sizeof(void*);
		_memory += obj_size;
		residualSize -= obj_size();

		new (obj)T; //  Initialize memory !
		return obj;
	}

	void Delete(T* obj) {
     //  Free memory !
		obj->~T(); //  Show call object destructors !
		//  Take a pointer size space from the released memory to store the address of the next node !
		*(void**)obj = _freeList; //  take obj Before the memory pointed to ( Save pointer length ) Bytes of memory do next Pointer memory !
		_freeList = obj;
	}

private:
	char* _memory = nullptr; //  The first address of the requested memory !
	void* _freeList = nullptr; //  Free memory chain header pointer !
	size_t residualSize = 0;     //  Remaining memory size !
};