# time a function using time.time() and the a @ function decorator
# tested with Python24  vegaseat  21aug2005
import time
def print_timing(func):
  def wrapper(*arg):
    t1 = time.time()
    res = func(*arg)
    t2 = time.time()
    print '%s took %0.3f ms' % (func.func_name, (t2-t1)*1000.0)
    return res
  return wrapper
# declare the @ decorator just before the function, invokes print_timing()
@print_timing
def getPrimeList(n):
  """ returns a list of prime numbers from 2 to < n using a sieve algorithm"""
  if n < 2: return []
  if n == 2: return [2]
  # do only odd numbers starting at 3
  s = range(3, n+1, 2)
  # n**0.5 may be slightly faster than math.sqrt(n)
  mroot = n ** 0.5
  half = len(s)
  i = 0
  m = 3
  while m <= mroot:
    if s[i]:
      j = (m*m-3)//2
      s[j] = 0
      while j < half:
        s[j] = 0
        j += m
    i = i+1
    m = 2*i+3
  return [2]+[x for x in s if x]
if __name__ == "__main__":
  print "prime numbers from 2 to <10,000,000 using a sieve algorithm"
  primeList = getPrimeList(10000000)
  time.sleep(2.5)
"""
my output -->
prime numbers from 2 to <10,000,000 using a sieve algorithm
getPrimeList took 4750.000 ms
"""