On 1 July 2013 14:14, Chris Angelico <ros...@gmail.com> wrote:
> On Mon, Jul 1, 2013 at 10:59 PM, Neil Cerutti <ne...@norwich.edu> wrote:
>> On 2013-06-30, Chris Angelico <ros...@gmail.com> wrote:
>>> So, here's a challenge: Come up with something really simple,
>>> and write an insanely complicated - yet perfectly valid - way
>>> to achieve the same thing. Bonus points for horribly abusing
>>> Python's clean syntax in the process.
>>>
>>> Go on, do your worst!
>>
>> I've often thought it was redundant for Python to support 'if'
>> when it has dictionaries, cf the rationale for having no
>> 'switch'.
>>
>> valid_name = None
>> while not valid_name:
>> name = input("Enter your name: ")
>> valid_name = {
>> True: lambda: print("No name longer than 20 letters."),
>> False: lambda: True,
>> }[len(name) > 20]()
>>
>> Much better.
>
> Good! Good! But, waaaah. Waaaah.
>
> def get_name():
> while True:
> name = input("Enter your name: ")
> yield {
> True: lambda: print("No name longer than 20 letters."),
> False: lambda: name,
> }[len(name) > 20]()
> name = next(filter(None,get_name()))
Oh, cruel. But you can do worse. Who needs "while" when you have
filter(iter(FUNCTION, object()))?
def get_name():
name = input("Enter your name: ")
return [
lambda: name,
lambda: print("No name longer than 20 letters."),
][len(name) > 20]()
name = next(filter(None, iter(get_name, object())))
But who needs *any* of this! Defining functions is so old-hat. It's
all already in the standard library (using only assignments and function-calls):
from functools import partial
from operator import getitem, ge, methodcaller
from itertools import compress, tee
apply = methodcaller("__call__")
ret_true = partial(getitem, [True], 0)
print_invalid = partial(print, "No name longer than 20 letters.")
inputs = iter(partial(input, "Enter your name: "), ...)
inputs, valid = tee(inputs)
valid = map(len, valid)
valid = map(partial(ge, 20), valid)
side_effect_valid = map(partial(getitem, [print_invalid, ret_true]), valid)
side_effect_valid = map(apply, side_effect_valid)
valid_inputs = compress(inputs, side_effect_valid)
name = next(valid_inputs)
Which can be "neatly" expressed as two statements (I'm struggling to
got it to one without those evil lambdas):
from functools import partial
from operator import getitem, ge, methodcaller
from itertools import compress, tee
inputs, valid = tee(iter(partial(input, "Enter your name: "), ...))
name = next(
compress(
inputs,
map(
methodcaller("__call__"),
map(
partial(
getitem,
[
partial(print, "No name longer than 20 letters."),
partial(getitem, [True], 0)
]
),
map(
partial(ge, 20),
map(len, valid)
)
)
)
)
)
Beautiful, see?
Of course, the most powerful function deals with this much more quickly:
exec("""
while True:
name = input("Enter your name: ")
if len(name) <= 20:
break
else:
print("No name longer than 20 letters.")
""")
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