Putting Maya back to it’s start up state, for Python’s sake

The node editor project is beginning to become bigger and bigger. Where I was first just handling basically everything in a giant nv_Node.py file, I realized that this was becoming a major ball ache while working. So I started to split everything up in their own nice little modules, which introduced me to the error message of hell:

super(type, obj): obj must be an instance or subtype of type

Which I got basically every time I needed to reload part of the project, but never when it was launched for the first time. I’m not going to pretend to fully understand how Python’s module importing works exactly and I’m also sure I have some bad programming designs in my code as well. But since I wanted to continue with this project over the holidays without a complete re-write, I went looking for another solution.

Luckily I happened upon this post by Nick Rodgers: https://medium.com/@nicholasRodgers/sidestepping-pythons-reload-function-without-restarting-maya-2448bab9476e His solution is pretty smart and saves so much time when you’re editing files all over the place. It deletes the previous imports so they’ll get imported freshly every time. Just posting it here in case I’ll need it again and can’t find the post anymore.

import inspect
from os.path import dirname
import sys


# I'm going to define this little function to make this cleaner
# It's going to have a flag to let you specify the userPath you want to clear out
# But otherwise I'd going to assume that it's the userPath you're running the script from (__file__)
def resetSessionForScript(userPath=None):
    if userPath is None:
        userPath = dirname(__file__)
    # Convert this to lower just for a clean comparison later
    userPath = userPath.lower()

    print userPath

    toDelete = []
    # Iterate over all the modules that are currently loaded
    for key, module in sys.modules.iteritems():
        # There's a few modules that are going to complain if you try to query them
        # so I've popped this into a try/except to keep it safe
        try:
            # Use the "inspect" library to get the moduleFilePath that the current module was loaded from
            moduleFilePath = inspect.getfile(module).lower()

            # Don't try and remove the startup script, that will break everything
            if moduleFilePath == __file__.lower():
                continue

            # If the module's filepath contains the userPath, add it to the list of modules to delete
            if moduleFilePath.startswith(userPath):
                print "Removing %s" % key
                toDelete.append(key)
        except:
            pass

    # If we'd deleted the module in the loop above, it would have changed the size of the dictionary and
    # broken the loop. So now we go over the list we made and delete all the modules
    for module in toDelete:
        del (sys.modules[module])