bonus.py

from time import perf_counter
from array import array
from contextlib import contextmanager

@contextmanager
def timing(label: str):
    t0 = perf_counter()
    yield lambda: (label, t1 - t0)
    t1 = perf_counter()

with timing('Array tests') as total:
    with timing('Array creation innermul') as inner:
        x = array('d', [0] * 1000000)

    with timing('Array creation outermul') as outer:
        x = array('d', [0]) * 1000000


print('Total [%s]: %.6f s' % total())
print('    Timing [%s]: %.6f s' % inner())
print('    Timing [%s]: %.6f s' % outer())

# Total [Array tests]: 0.064896 s
#    Timing [Array creation innermul]: 0.064195 s
#    Timing [Array creation outermul]: 0.000659 s

closures-bind-late-1.py

def mult_function_generator(max):
    for i in range(max):
        yield lambda x: x * i

mult_functions = list(mult_function_generator(3))
print([func(3) for func in mult_functions])
# Oh crap, it's [6, 6, 6], not [0, 3, 6]

closures-bind-late-2.py

mult_functions = mult_function_generator(3)
mult_zero = next(mult_functions)
mult_zero
# <function ...>

closures-bind-late-3.py

mult_zero.__closure__
# (<cell at 0x..., int object at 0x...>,)

cell_zero = mult_zero.__closure__[0]
cell_zero.cell_contents
# 0

mult_one = next(mult_functions)
cell_one = mult_one.__closure__[0]
cell_one.cell_contents
# 1
# So far so good. But...
cell_zero.cell_contents
# 1
# Crap!
cell_zero is cell_one
# True
# Okay fine

closures-bind-late-4.py

def mult_function_generator_1(max):
    for i in range(max):
        yield (lambda i: lambda x: x * i)(i)

closures-bind-late-5.py

def mult_function_generator_2(max):
    for i in range(max):
        yield functools.partial(lambda x, i: x * i, i=i)

closures-bind-late-6.py

def mult_function_generator_3(max):
    for i in range(max):
        yield lambda x, i=i: x * i