Dynamically create operators that can add custom objects

__init__.py

# for http://blender.stackexchange.com/q/56741/935

bl_info = {
    'version': (1, 0),
    'blender': (2, 75, 0),
    'author': 'sambler',
    'name': 'Custom Object Factory',
    'location': 'blender',
    'description': 'Create multiple custom operators that create objects' ,
    'warning': 'only for testing',
    'category': 'test',
}

import bpy
import os

# this example uses the following file layout
# located in blender's addons folder
#object_factory/
#    __init__.py
#    custom_data/
#        Female_body
#        RacingCar
#        iPhone
#        Male_body
#        Tank
#        Toaster

# this is the dirname that contains the object data
# it is located in the addon folder next to this file
obj_dir_name = 'custom_data'

# these names match files located in the addons obj_dir_name
# we can't access the filesystem during registration so
# we need to maintain this list manually
obj_list = [
    'Female_body',
    'RacingCar',
    'iPhone',
    'Male_body',
    'Tank',
    'Toaster'
]

# this holds the custom operators so we can cleanup when turned off
custom_items = []

def addCustomItems():
    for obj_name in obj_list:
        op_name = 'object.add_custom_' + obj_name.lower()
        data_file = os.path.join(os.path.dirname(__file__), obj_dir_name, obj_name)
        nc = type(  'DynOp_' + obj_name,
                    (CustomObjectBase, ),
                    {'bl_idname': op_name,
                    'bl_label': 'Add a ' + obj_name,
                    'bl_description': 'This adds an ' + obj_name,
                    'obj_file': data_file
                })
        custom_items.append(nc)
        bpy.utils.register_class(nc)

def clearCustomItems():
    for c in custom_items:
        bpy.utils.unregister_class(c)

class CustomObjectBase(bpy.types.Operator):
    """Base for adding a custom object"""
    bl_idname = 'object.add_custom_item'
    bl_label = 'Add Item'
    bl_description ='Base operator for adding custom objects'
    bl_options = {'REGISTER', 'UNDO'}

    obj_file = bpy.props.StringProperty()

    def execute(self, context):
        with open(self.obj_file, 'r') as f:
            # read data and create mesh
            obj_name = os.path.basename(self.obj_file)
            obj = bpy.data.objects.new(obj_name, None)
            context.scene.objects.link(obj)
        return {'FINISHED'}

class AddCustomObjects(bpy.types.Menu):
    """My custom objects menu"""
    bl_label = 'Custom Objects'
    bl_idname = 'AddCustomObjects'

    def draw(self, context):
        lo = self.layout
        for o in custom_items:
            lo.operator(o.bl_idname, icon='OUTLINER_OB_ARMATURE')

def menu_func(self, context):
    self.layout.menu('AddCustomObjects', text='Custom Objects', icon='OUTLINER_OB_ARMATURE')

def register():
    bpy.utils.register_class(CustomObjectBase)
    addCustomItems()
    bpy.utils.register_class(AddCustomObjects)
    bpy.types.INFO_MT_add.append(menu_func)

def unregister():
    bpy.types.INFO_MT_add.remove(menu_func)
    bpy.utils.unregister_class(AddCustomObjects)
    clearCustomItems()
    bpy.utils.unregister_class(CustomObjectBase)

if __name__ == '__main__':
    register()

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