Added Mobject.update capabilties, which should be nicer and lighter weight than using ContinualUpdateFromFunc all the time. Also changed the behavior of any Animation having its mobject automatically thrust up to the front of the screen

mobject/mobject.py

@@ -1,6 +1,4 @@
 
-
-
 import copy
 import itertools as it
 import numpy as np
@@ -22,6 +20,7 @@ from utils.paths import straight_path
 from utils.space_ops import angle_of_vector
 from utils.space_ops import complex_to_R3
 from utils.space_ops import rotation_matrix
+from utils.simple_functions import get_num_args
 from functools import reduce
 
 
@@ -46,6 +45,7 @@ class Mobject(Container):
         self.color = Color(self.color)
         if self.name is None:
             self.name = self.__class__.__name__
+        self.updaters = []
         self.init_points()
         self.generate_points()
         self.init_colors()
@@ -98,6 +98,8 @@ class Mobject(Container):
             setattr(self, attr, func(getattr(self, attr)))
         return self
 
+    # Displaying
+
     def get_image(self, camera=None):
         if camera is None:
             from camera.camera import Camera
@@ -142,6 +144,42 @@ class Mobject(Container):
             self.target = self.copy()
         return self.target
 
+    # Updating
+
+    def update(self, dt):
+        for updater in self.updaters:
+            num_args = get_num_args(updater)
+            if num_args == 1:
+                updater(self)
+            elif num_args == 2:
+                updater(self, dt)
+            else:
+                raise Exception(
+                    "Mobject updater expected 1 or 2 "
+                    "arguments, %d given" % num_args
+                )
+
+    def get_time_based_updaters(self):
+        return [
+            udpater
+            for updater in self.updaters
+            if get_num_args(updater) == 2
+        ]
+
+    def get_updaters(self):
+        return self.updaters
+
+    def add_updater(self, update_function):
+        self.updaters.append(update_function)
+
+    def remove_updater(self, update_function):
+        while update_function in self.updaters:
+            self.updaters.remove(update_function)
+        return self
+
+    def clear_updaters(self):
+        self.updaters = []
+
     # Transforming operations
 
     def apply_to_family(self, func):
@@ -604,6 +642,7 @@ class Mobject(Container):
 
     def get_color(self):
         return self.color
+
     ##
 
     def save_state(self, use_deepcopy=False):