importing modules/scripts in python

Question

So at work i'm developing a way for us to push out tools/plugins to the team as a whole. I actually have the system up and running and it's completely dynamic except for the topic i'm about to talk about (this is all done in python). On start up Maya checks the local folder against a folder on the server and checks to see if they are different and handles and copying down files/dirs that are needed as well as the deleting of old plugins that we delete on the server. The system is flexible enough that users can create custom shelves of all the plugins and we can re organize the folders in the back end without breaking the shelves of all the users. The plugins are accessed through a drop down menu in Maya's main interface and we can add sub folders into the system and plugins freely without messing with the code. We can also arrange the order at which menu items and plugins can be displayed through a simple numbering system of the folders.

This is all working fine until I get to making plugins, when they import a module in their folder, dynamic as well. So when I start moving the plugins folder around the root directory, if I have an imported module that I created the path for, the imported modules path in the plugin script is now wrong at that point. I already have a way of getting the proper path info to the plugin through my menu setup. I'm having issue with the import of the module and accessing classes with in that module.

so If the standard for importing a module's class

from fileName import className

and the __import__ way that i'm using looks like.

className = __import__("folderN.folderN.folderN.fileName", {}, {}, ["className"])

But with that method I loose the ability to just call on that class name like I can with the regular from import method. I got around that by doing

className = className.className

but this is a rather ugly method and i'd prefer to be able to just import and call on the name without doing that extra step. I do not know this import method very well and I know i'm missing some things with it.

Am I just going about this import process the wrong way? Is there a way to make it look into the local directory for the plugin without appending to maya's paths that way i can just do the regular way of importing method without a weird path that has to change anytime I move the plugin?

Answer 1

__import__ doesn't work they way you are assuming. It returns a module object for the import path provided, with a guarantee that all the children you specify in the list have been explicitly imported. For classes, it doesn't really make a difference.

mod = __import__('a.b', {}, {}, ['c', 'd'])

Is more accurately the equivalent of

import a.b
try:
    import a.b.c
except ImportError:
    pass
try:
    import a.b.d
except ImportError:
    pass
mod = a.b

What you actually probably want here is something like

child = getattr(__import__(import_path, {}, {}, [child_name]), child_name)

As to your versioning and distribution system, have you looked at using an SCM/VCS like SVN or GIT, and/or a package management system? These give you much better change tracking and synchronization than a straight file share, and you could easily integrate them with a sync/install script on your client machines that could be customizable as needed for the client's specific configuration demands.