Limits of Metaprogramming

[Wilson]

Hi all,

I have an interesting problem that I'm hoping can be solved with
metaprogramming, but I don't know how far Python supports code
generation (and I don't know if I'm taking the correct approach
either... hence why I'm asking on this group):

I'd like to write a program that writes/manipulates a statemachine. My
idea was that I would define states in a .py file along with their
transitions and other metadata. I could then write a suite of programs
that would manipulate these states in interesting ways, such as
generate diagrams and documentation, test suites, do verifications and
also edit them. These programs would import the .py file and use
introspection upon the module's classes (states would be modelled as
classes). For example, a documentation tool could use graphviz to draw
the statediagram with the transition table and docstring...

My problem is that I don't know if it's possible to edit these states
and then write them back to .py. Firstly, if my editing tool was to
create a new state, I would want to create the class (using type) and
attach it to the imported state module somehow. I can't find
information on whether this is possible. Secondly, I'd like to
manipulate the class and then use the inspect module to get the source
and write it back to file. Now I'm pretty sure the inspect module will
only write the source code as found in the original .py file. Is there
a way to generate the code for a class or other python objects in a
generic way? Or will I have to bite the bullet and write to custom
file and generate code from that (like glade with XML)? Or is there
another solution with templates that I'm over looking?

Having the classes in memory, editing their attributes, adding methods
and then serialising them to code has an elegance to it in my mind and
would hopefully simplify things. The result would be directly
executable by the interpreter itself and editable by python
developers. But I fear that I may need an intermediary notation/format
for storage. Any advice/hints would be very useful.

Thanks,
Paul