模拟实现定制删除器的SharedPtr_自定义删除仿函数deleter()-CSDN博客

本文链接：https://blog.csdn.net/agate_zhang/article/details/70241034

模拟实现定制删除器的SharedPtr

上篇博客里介绍了三种智能指针，模拟了三种智能指针的简单实现。

这里继续介绍智能指针SharedPtr，利用仿函数定制删除器

利用仿函数来解决C++中出现的new 、delete等匹配问题

在C++中有关内存处理方面的操作符或函数有

new----------delete malloc-----------free fopen-----------fclose lock----------unlock

#include 
    
    
     
     
template
     
     
      
      
class Delete
{
public:
	void operator()(T* ptr)
	{
		cout << "Delete" << endl;
		delete ptr;
		ptr = NULL;
	}
};
template
      
      
       
       
class DeleteArray
{
public:
	void operator()(T* ptr)
	{
		cout << "DeleteArray" << endl;
		delete[] ptr;
	}
};
template
       
       
        
        
class Free
{
public:
	void operator()(T* ptr)
	{
		cout << "Free" << endl;
		free(ptr);
	}
};
template
        
        
          class Fclose { public: void operator()(T*& ptr) { cout << "Fclose" << endl; fclose(ptr); ptr = NULL; } }; template 
         
           > class SharedPtr { public: SharedPtr(T* ptr) :_ptr(ptr) , _refCount(new int(1)) {} ~SharedPtr() { Release(); } T& operator*() { return *_ptr; } T*operator->() { return _ptr; } inline void Release() { if (--*_refCount==0) { _del(_ptr); delete _refCount; _refCount = NULL; } } SharedPtr(const SharedPtr 
          
            & sp) :_ptr(sp._ptr) , _refCount(sp._refCount) { (*_refCount)++; } SharedPtr 
           
             & operator=(const SharedPtr 
            
              & sp) { if (_ptr != sp._ptr) { Release(); _ptr = sp._ptr; _refCount = sp._refCount; (*_refCount)++; } return *this; } protected: T* _ptr; int* _refCount; Del _del; }; void TestSharedPtr() { SharedPtr 
             
               ap1(new int(10)); SharedPtr 
              
                ap2 ( ap1); SharedPtr 
               
                 ap3(new int(20)); ap2=ap3; SharedPtr 
                
                  > sp2(fopen("test.txt", "rb")); }

通过定制删除器来避免内存回收时的问题。