Thu, 10 Aug 2006

C++ Wrapper for libsndfile, Part 4.

I got some email from Jaq who said:

"You don't actually give a good reason for not wanting a close() method on SndfileHandle; your reasons for not wanting open() are good, but surely a handle needs a way of closing itself? Or does the API overload object deletion with the closing of the handle too?"

So first of all, I should have stated that my current candidate header file is available here. The SndfileHandle object is designed to be used with the Resource Acquisition Is Initialization pattern. In particular, the object will close the file and release all allocations when it goes out of scope. For instance: 

  {
      SndfileHandle file ("foo.wav") ;

      // Do something with file which gets closed automatically
      // when file goes out of scope.
  }

So what's the problem with the close() method? Well, its very similar to the problems with the open() method. Lets look at an example: 

  SndfileHandle file1 ("foo.wav") ;

  // Make file2 == file1
  SndfileHandle file2 = file1 ;

  // Close file1
  file1.close ("bar.wav") ;

Obviously, the handle associated with file1 should be closed, but what about file2? Should that be closed or remain open?

The fact that its not obvious means that its best left out. If anyone really wants to make sure that a SndfileHandle is closed they can do: 

  SndfileHandle file1 ("foo.wav") ;

  // Make file2 == file1
  SndfileHandle file2 = file1 ;

  // Close file1
  file1 = SndfileHandle () ;

In this case its a little more obvious that file1 and file2 now refer to different handles.

Posted at: 20:54 | Category: CodeHacking/libsndfile | Permalink