cartpole fix (openai#457)

minor fixes related to configure() and cartpole

gym/core.py

@@ -311,9 +311,7 @@ def __init__(self, env=None):
 
         self._update_wrapper_stack()
         if env and env._configured:
-            # TODO: CartPole currently calls configure on `make`. Fix this so that we can use WrapAfterConfigureError
-            # raise error.WrapAfterConfigureError("Attempted to wrap env {} after .configure() was called. All wrappers must be applied before calling .configure()".format(env))
-            logger.warn("Attempted to wrap env {} after .configure() was called. All wrappers must be applied before calling .configure()".format(env))
+            logger.warning("Attempted to wrap env %s after .configure() was called.", env)
 
     def _update_wrapper_stack(self):
         """

gym/envs/classic_control/cartpole.py

@@ -43,17 +43,10 @@ def __init__(self):
         self.observation_space = spaces.Box(-high, high)
 
         self._seed()
-        self.reset()
         self.viewer = None
 
         self.steps_beyond_done = None
 
-        # Just need to initialize the relevant attributes
-        self._configure()
-
-    def _configure(self, display=None):
-        self.display = display
-
     def _seed(self, seed=None):
         self.np_random, seed = seeding.np_random(seed)
         return [seed]
@@ -87,7 +80,7 @@ def _step(self, action):
             reward = 1.0
         else:
             if self.steps_beyond_done == 0:
-                logger.warn("You are calling 'step()' even though this environment has already returned done = True. You should always call 'reset()' once you receive 'done = True' -- any further steps are undefined behavior.")
+                logger.warning("You are calling 'step()' even though this environment has already returned done = True. You should always call 'reset()' once you receive 'done = True' -- any further steps are undefined behavior.")
             self.steps_beyond_done += 1
             reward = 0.0
 
@@ -118,7 +111,7 @@ def _render(self, mode='human', close=False):
 
         if self.viewer is None:
             from gym.envs.classic_control import rendering
-            self.viewer = rendering.Viewer(screen_width, screen_height, display=self.display)
+            self.viewer = rendering.Viewer(screen_width, screen_height)
             l,r,t,b = -cartwidth/2, cartwidth/2, cartheight/2, -cartheight/2
             axleoffset =cartheight/4.0
             cart = rendering.FilledPolygon([(l,b), (l,t), (r,t), (r,b)])