I'm making a program that consists of a main engine + plugins. Both
are in Python. My question is, how do I go about importing arbitrary
code and have it be able to use the engine's functions, classes, etc?
First, here's how it's laid out on the filesystem:
-mainstarterscript.py
-<engine>
-__init__.py
-[whole bunch of files]
-<plugin>
-__init__.py
-main.py
-[whole bunch of files]
So you'd execute the whole thing with ./mainstarterscript.py, which
imports engine. Engine initializes, then executes plugin somehow.
Plugin needs to be able to call functions in engine, and vice versa.
Although various IPC methods would probably work, I think there's
gotta be an easier and more straightforward way to do it.
I use execfile to execute the plugin's __init__.py script. I insert
some globals from engine into it so that __init__ can use them.
__init__.py also imports plugin/main.py, which uses functions the
engine functions, and so must import __init__.py. The problem is,
when main imports __init__, the inserted globals aren't there, so it
dies. So I've tried to make some globals in __init__ that simply map
them to the engine's globals. Here's roughly how:
#plugin/__init__.py
engine_globals = {}
if __name__ == '__builtin__': #run via execfile
global engine_globals
engine_globals = globals() #I don't really want all the globals, but
in my real code I go through them one by one
else: #imported from one of the other scripts in plugin dir.
pass
import main #among other things
# end __init__.py
# plugins/main.py
import __init__
__init__.engine_globals.['some_function'](args)
#do other stuff
#end main.py
#engine/__init__.py
def some_function(args):
pass
sys.argv.append('plugins')
execfile('plugins/__init__.py')
When main.py imports plungin/__init__, it reinitializes engine_globals
to {}, of course. But I can't think of a way not to initialize it to
something, thus overwriting the original, because it needs to be in
the namespace.. Essentially, I want a global to not reset itself if
it's already set.
So how do I go about doing this? Am I on the right track? Should I
be __import__'ing plugins instead of execfile'ing them?
Thanks,
Nick
