Finally in C++

后端未结

关注

 6  1546

南旧 2020-12-28 08:33

Is this a good way to implement a Finally-like behavior in standard C++? (Without special pointers)

class Exception : public Exception
    { public: virtual


      
      
        
          6条回答        

        
                    
            
            
                         
                
              
              
                
                   予麋鹿
                                             
                
                
                (楼主)
            
              
              
                2020-12-28 09:27
              

            
            
                        
The standard answer is to use some variant of resource-allocation-is-initialization abbreviated RAII.  Basically you construct a variable that has the same scope as the block that would be inside the block before the finally, then do the work in the finally block inside the objects destructor.

try {
   // Some work
}
finally {
   // Cleanup code
}


becomes

class Cleanup
{
public:
    ~Cleanup()
    {
        // Cleanup code
    }
}

Cleanup cleanupObj;

// Some work.


This looks terribly inconvenient, but usually there's a pre-existing object that will do the clean up for you.  In your case, it looks like you want to destruct the object in the finally block, which means a smart or unique pointer will do what you want:

std::unique_ptr