Docstrings.

[python-bulletml.git] / bulletml / impl.py

diff --git a/bulletml/impl.py b/bulletml/impl.py
index 2c938d2..65d234a 100644 (file)
--- a/bulletml/impl.py
+++ b/bulletml/impl.py
@@ -7,7 +7,7 @@ from __future__ import division
 
 import math
 
-from bulletml import parser, errors
+from bulletml import parser
 
 # TODO(jfw): This is very non-Pythonic, it's pretty much just the
 # BulletML reference ActionImpl translated to Python.
@@ -37,6 +37,7 @@ class Action(object):
         self.params = params
         self.rank = rank
         self.pc = -1
+        self.finished = False
         if parent:
             self.copy_state(parent)
 
@@ -44,16 +45,15 @@ class Action(object):
         return "%s(pc=%r, actions=%r)" % (
             type(self).__name__, self.pc, self.actions)
 
-    @property
-    def finished(self):
-        return self.pc is None
-
     def vanish(self):
+        """End this action and its parents."""
         if self.parent:
             self.parent.vanish()
         self.pc = None
+        self.finished = True
 
     def copy_state(self, other):
+        """Copy fire/movement state from other to self."""
         self.direction_frames = other.direction_frames
         self.direction = other.direction
         self.aiming = other.aiming
@@ -66,6 +66,7 @@ class Action(object):
         self.previous_fire_speed = other.previous_fire_speed
 
     def step(self):
+        """Advance by one frame."""
         created = []
 
         if self.speed_frames > 0:
@@ -99,6 +100,7 @@ class Action(object):
                 self.repeat -= 1
                 if self.repeat <= 0:
                     self.pc = None
+                    self.finished = True
                     if self.parent is not None:
                         self.parent.copy_state(self)
                         self.owner.replace(self, self.parent)
@@ -238,9 +240,9 @@ class Bullet(object):
         self.actions = []
         if rank is None:
             rank = parent.rank if parent else 0.5
-        for action, params in actions:
-            # New bullets reset the parent hierarchy.
-            self.actions.append(Action(self, None, action, params, rank))
+        # New bullets reset the parent hierarchy.
+        self.actions = [Action(self, None, action, params, rank)
+                        for action, params in actions]
 
     def __repr__(self):
         return ("%s(%r, %r, accel=%r, direction=%r, speed=%r, "
@@ -256,10 +258,11 @@ class Bullet(object):
             return self.direction
         else:
             return math.degrees(
-                math.atan2(self.target.x - self.x, self.target.y - self.y))
+                math.atan2(self.target.x - self.x, self.y - self.target.y))
 
     @property
     def finished(self):
+        """Check if this bullet is finished running."""
         for action in self.actions:
             if not action.finished:
                 return False
@@ -273,6 +276,7 @@ class Bullet(object):
         self.actions = []
 
     def replace(self, old, new):
+        """Replace an active action with another."""
         try:
             idx = self.actions.index(old)
         except ValueError:
@@ -281,12 +285,15 @@ class Bullet(object):
             self.actions[idx] = new
 
     def step(self):
+        """Advance by one frame."""
         created = []
 
         for action in self.actions:
             created.extend(action.step())
 
         direction = math.radians(self.direction)
+        self.px = self.x
+        self.py = self.y
         self.x += self.mx + math.sin(direction) * self.speed
         self.y += self.my - math.cos(direction) * self.speed
 
@@ -295,6 +302,7 @@ class Bullet(object):
     @classmethod
     def FromDoc(cls, doc, params=(), x=0, y=0, speed=0, direction=0,
                 target=None, rank=0.5):
+        """Construct a bullet from top-level actions in a document."""
         actions = [act(params, rank) for act in doc.top]
         return cls(x, y, direction, speed, target, actions, rank=rank)