[CMake] CMake 2.4.1/VC71 Why the wierd <project>.dir subdirs?

[Rob Mathews]

CMake seems to be generating intermediate directories called
<project-name>.dir and placing the obj files under them. 

Ie, if my project is foo, then /foo/foo.dir/*.obj

I look in the code and see that this derives from
cmLocalVisual7Generator.cxx, which reads as follows. (The "#if 0" is my
addition)

std::string cmLocalVisualStudio7Generator
::GetTargetDirectory(cmTarget& target)
{
#if 0
why???? this replaces the old structure of <project>/Debug with
<project>/<project>.dir/Debug. What's the point????!!!
	std::string dir;
  dir += target.GetName();
  dir += ".dir";
  return dir;
#endif
  return ".";
}


As I say, what's the point?