Trying to create a simple add-on but Python keeps throwing errors

Question

I am trying to create a simple add-on that will automatically reload images in Blender. I managed to find a few scripts that helped me and when I press "Run Script" it works as expected. However, when I try to add it to the Add-On in Blender, I get this error:

AttributeError: '_RestrictData' object has no attribute 'images'

The line causing the problem is:

images = bpy.data.images

Here is the full script:

import bpy
import os
from threading import Timer

bl_info = {"name": "Auto Reload Addon", "category": "Object"}
last_mod = {}

def startup():
    images = bpy.data.images
    for img in images :
        if img.source == 'FILE' :
            path = img.filepath_from_user()
            statbuf = os.stat(path)
            last_mod[img.filepath_raw] = statbuf.st_mtime

def autoreload():
    images = bpy.data.images
    for img in images :
        if img.source == 'FILE' :
            path = img.filepath_from_user()
            statbuf = os.stat(path)
            if statbuf.st_mtime > last_mod[img.filepath_raw]:
                last_mod[img.filepath_raw] = statbuf.st_mtime        
                img.filepath = img.filepath.replace('\\old_folder\\','\\new_folder\\')
                img.reload()

def register():
    print("Auto Reloading Enabled")
    startup()
    rt = RepeatedTimer(1, autoreload) 

def unregister():
    print("Auto Reloading Disabled")

if __name__ == "__main__":
    register()

The RepeatedTimer is a class I found online that run a function every X seconds

I searched online and The kinds of solutions I saw is to use bpy.data after the register(), and it didn't let me call it like this:

if __name__ == "__main__":
    register() # This is called
    startup() # This wont even be called when the Add-on is enabled!

I understand that this has something to do with the import but I can't figure out what is wrong. I tried a few things that didn't even run.

Am I doing something really wrong here? again, the "Run Script" button works as expected, but I want to be able to disable and enable the script.

Answer 1

You cannot access Blender from a different thread. To create a periodically called function, use a modal operator with a timer.