Invaders from Space!

In this demo, we've designed an alien fleet that's invading and can shoot laser beams! Our current issue is that we want to make sure that the attack system won't overload the system resources, so we need a way to control how many laser beams are allowed at once. Using the Object Pool with a spawn limit can help us achieve this, while also preserving performance by allowing us to recycle the laser beams.

The Laser Beam:

# The base vector class:
class Vector3D(object):
   def __init__(self):
       self.x = 0.0
       self.y = 0.0
       self.z = 0.0

   def Set(self, x, y, z):
       self.x = x
       self.y = y
       self.z = z
   
   def Clean(self):
       self.x = 0.0
       self.y = 0.0
       self.z = 0.0


# The Laser Beam class:
class LaserBeam(object):
   def __init__(self):
       self.position = Vector3D()
   
   def Clean(self):
       self.position.Clean()

The Laser Beam Pool:

class LaserBeamPool(object):
   def __init__(self, reserve = 5, maxCapacity = 100):
       self.activeList = []
       self.reserveList = []

       self.maxCapacity = maxCapacity
       self.numberActive = 0
       self.numberReserved = 0
       self._InitializeReserve(reserve)
       
   def _InitializeReserve(self, reserve):
       for i in range(reserve + 1):
           tmp = LaserBeam()
           self.reserveList.append(tmp)
           self.numberReserved += 1
   
   def CanSpawn(self):
       return self.numberActive < self.maxCapacity

   def GetLaserBeam(self):
       '''
           NOTICE:
           In your code, make sure to check the spawn limit.
           you can either:
               1. Throw an exception
               2. Return None
               3. Spawn a new zombie anyways.

               We'll return None.
       '''
       if self.numberActive >= self.maxCapacity:
           return None
       
       if self.numberReserved == 0:
           tmp = LaserBeam()
           self.reserveList.append(tmp)
           self.numberReserved += 1
       
       laser = self.reserveList.pop()
       self.numberReserved -= 1

       self.activeList.append(laster)
       self.numberActive += 1

       laser.Clean()

       return laser

   def ReturnLaserBeam(self, laser):
       if laser in self.activeList:
           self.activeList.remove(laser)
           self.numberActive -= 1
           
           self.reserveList.append(laser)
           self.numberReserved += 1