Introspection at the module level?

[Roy Smith]

I've got a module that defines a bunch of constants:

OP_FOO = 1
OP_BAR = 2
OP_BAZ = 37

and so on.  The values are all unique.  I want to build, at module 
import time, a reverse map of these constants, i.e. I want to end up 
with:

{1: "OP_FOO", 2: "OP_BAR", 37: "OP_BAZ"}

I can find the appropriate symbols:

for name in dir():
   if name.startswith ("OP_"):
      print name

But I don't see how to get the values.  Getattr() is sort of what I 
want, but it works on objects, not modules.  Not to mention that I don't 
see how to get a handle to the module from inside the module, i.e. 
there's no "self".

What am I missing?