Module name to filename and back?

[Ron Adam]

Is there a function to find a filename from a dotted module (or package) name
without importing it?

The imp function find_module() doesn't work with dotted file names. And it
looks like it may import the file as it raises an ImportError error exception if
it can't find the module. (Shouldn't it raise an IOError instead?)

What I'm looking for is to be able to get the full module name when I have a
filename. And get the full filename when I have the module name. And do both
of these without importing the module.

modulename <==> filename
filename <==> modulename

Ron