Documenting a non-existing member with Doxygen

Define the attribute inside an if 0: block:

## @class X
## @brief this is useless
class X:
    if 0:
        ## @brief whatevs is a property that doesn't exist in spacetime
        ##
        ## It is designed to make bunny cry.
        whatevs = property

This will cause it to exist in the documentation (tested with doxygen 1.8.1.2-1 on debian-squeeze). The attribute will never be made to exist at runtime, and in fact it looks like the python bytecode optimizer eliminates if statement and its body altogether.