From: demarcus_at_hotmail_com@tellus.orb.dotsrc.org   
      
   > // GOOD (RAII)   
   > {   
   > 	CleanupType cleanup;   
   > 	dosomething();   
   > }   
   >   
   > // ????   
   > {   
   > 	try   
   > 	{   
   > 		dosomething();   
   > 		cleanup();   
   > 	}   
   > 	catch (const std::exception& ex)   
   > 	{   
   > 		cleanup();   
   > 	}   
   > 	catch (...)   
   > 	{   
   > 		cleanup();   
   > 	}   
   > }   
   >   
   > Why is the 2nd (RAII) approach superior to the third approach?  I   
   > presume there's more to it than "appearance"?  While the third   
   > approach looks more complicated, it doesn't have to worry about a   
   > "CleanupType"...   
   >   
      
   I see at least two problems with the third example.   
      
   [*] You should be very careful with catching ellipsis (...). If you do   
   you must at least rethrow, like this:   
      
   catch (...)   
   {   
        cleanup();   
        throw;   
   }   
      
   (I challenge anyone reading this to come up with examples where one   
   would ever need to catch ellipsis)   
      
   [*] You get into problems where you want to return early (opposite of   
   Single-Exit-Point). Here's an example that would be cumbersome with   
   your approach.   
      
   int randomNumber()   
   {   
        try   
        {   
           dosomething();   
      
           lockWeatherVariable();   
           switch( theWeather )   
           {   
              case SUNNY:   
                 cleanup();   
                 unlockWeatherVariable();   
                 return 35;   
              case CLOUDY:   
                 cleanup();   
                 unlockWeatherVariable();   
                 return 93;   
              case RAINY:   
                 cleanup();   
                 unlockWeatherVariable();   
                 return 62;   
              default:   
                 break;   
           }   
        }   
        catch( ... )   
        {   
           cleanup();   
           unlockWeatherVariable();   
           // Do you see the error that leaked in here?   
           throw;   
        }   
      
        cleanup();   
        unlockWeatherVariable();   
        return 4711;   
   }   
      
   Compare above with the following:   
      
   int randomNumber()   
   {   
        ScopedLock lock;   
        CleanupType cleanup;   
      
        dosomething();   
      
        switch( theWeather )   
        {   
           case SUNNY:   
              return 35;   
           case CLOUDY:   
              return 93;   
           case RAINY:   
              return 62;   
           default:   
              break;   
        }   
      
        return 4711;   
   }   
      
   RAII is a beautiful way of relieving your mind from what need to be   
   cleaned up, where and when.   
      
   Regards,   
   Daniel   
      
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