script_watcher.py

import bpy
import sys
import os
import traceback

class ModalTimerOperator(bpy.types.Operator):
    """Operator which runs its self from a timer"""
    bl_idname = "wm.modal_timer_operator"
    bl_label = "Modal Timer Operator"

    _timer = None
    prev=''
    
    
    def modal(self, context, event):
        if event.type in {'RIGHTMOUSE', 'ESC'}:
            self.cancel(context)
            return {'CANCELLED'}

        if event.type == 'TIMER':
            curr= open(sys.argv[-1]).read()
            if not self.prev==curr:
                print("%s changed" % sys.argv[-1])
                try:
                    exec(curr)
                    self.prev=curr
                    print('done ok');
                except Exception as e:
                    exc_type, exc_obj, exc_tb = sys.exc_info()
                    print(traceback.format_exc())
                    self.prev=curr
                    pass
                    

        return {'PASS_THROUGH'}

    def execute(self, context):
        wm = context.window_manager
        self._timer = wm.event_timer_add(0.1, window=context.window)
        wm.modal_handler_add(self)
        return {'RUNNING_MODAL'}

    def cancel(self, context):
        wm = context.window_manager
        wm.event_timer_remove(self._timer)


def register():
    bpy.utils.register_class(ModalTimerOperator)


def unregister():
    bpy.utils.unregister_class(ModalTimerOperator)


if __name__ == "__main__":
    register()

    # test call
    bpy.ops.wm.modal_timer_operator()