4_2_func.py

def fib(n):    # write Fibonacci series up to n
    """Print a Fibonacci series up to n."""
    a, b = 0, 1
    while a < n:
        print(a, end=' ')
        a, b = b, a+b
    print()

# Now call the function we just defined:
fib(2000)
# 0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597

fib
# <function fib at 10042ed0>
f = fib
f(100)
# 0 1 1 2 3 5 8 13 21 34 55 89

fib(0)
print(fib(0))
# None

def fib2(n):  # return Fibonacci series up to n
    """Return a list containing the Fibonacci series up to n."""
    result = []
    a, b = 0, 1
    while a < n:
        result.append(a)    # see below
        a, b = b, a+b
    return result

f100 = fib2(100)    # call it
f100                # write the result
# [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]


def ask_ok(prompt, retries=4, reminder='Please try again!'):
    while True:
        ok = input(prompt)
        if ok in ('y', 'ye', 'yes'):
            return True
        if ok in ('n', 'no', 'nop', 'nope'):
            return False
        retries = retries - 1
        if retries < 0:
            raise ValueError('invalid user response')
        print(reminder)


i = 5

# def f(arg=i):
#     print(arg)

# i = 6
# f()

# def f(a, L=[]):
#     L.append(a)
#     return L

# print(f(1))
# print(f(2))
# print(f(3))

# def f(a, L=None):
#     if L is None:
#         L = []
#     L.append(a)
#     return L

def parrot(voltage, state='a stiff', action='voom', type='Norwegian Blue'):
    print("-- This parrot wouldn't", action, end=' ')
    print("if you put", voltage, "volts through it.")
    print("-- Lovely plumage, the", type)
    print("-- It's", state, "!")

parrot(1000)                                          # 1 positional argument
parrot(voltage=1000)                                  # 1 keyword argument
parrot(voltage=1000000, action='VOOOOOM')             # 2 keyword arguments
parrot(action='VOOOOOM', voltage=1000000)             # 2 keyword arguments
parrot('a million', 'bereft of life', 'jump')         # 3 positional arguments
parrot('a thousand', state='pushing up the daisies')  # 1 positional, 1 keyword

# parrot()                     # required argument missing
# parrot(voltage=5.0, 'dead')  # non-keyword argument after a keyword argument
# parrot(110, voltage=220)     # duplicate value for the same argument
# parrot(actor='John Cleese')  # unknown keyword argument

def function(a):
    pass

# function(0, a=0)
# Traceback (most recent call last):
#   File "<stdin>", line 1, in <module>
# TypeError: function() got multiple values for keyword argument 'a'

def cheeseshop(kind, *arguments, **keywords):
    print("-- Do you have any", kind, "?")
    print("-- I'm sorry, we're all out of", kind)
    for arg in arguments:
        print(arg)
    print("-" * 40)
    for kw in keywords:
        print(kw, ":", keywords[kw])

cheeseshop("Limburger", "It's very runny, sir.",
           "It's really very, VERY runny, sir.",
           shopkeeper="Michael Palin",
           client="John Cleese",
           sketch="Cheese Shop Sketch")

# -- Do you have any Limburger ?
# -- I'm sorry, we're all out of Limburger
# It's very runny, sir.
# It's really very, VERY runny, sir.
# ----------------------------------------
# shopkeeper : Michael Palin
# client : John Cleese
# sketch : Cheese Shop Sketch

def write_multiple_items(file, separator, *args):
    file.write(separator.join(args))

def concat(*args, sep="/"):
    return sep.join(args)

concat("earth", "mars", "venus")
# 'earth/mars/venus'
concat("earth", "mars", "venus", sep=".")
# 'earth.mars.venus'

list(range(3, 6))            # normal call with separate arguments
[3, 4, 5]
args = [3, 6]
list(range(*args))            # call with arguments unpacked from a list
[3, 4, 5]

# def parrot(voltage, state='a stiff', action='voom'):
#     print("-- This parrot wouldn't", action, end=' ')
#     print("if you put", voltage, "volts through it.", end=' ')
#     print("E's", state, "!")

d = {"voltage": "four million", "state": "bleedin' demised", "action": "VOOM"}
parrot(**d)
# -- This parrot wouldn't VOOM if you put four million volts through it. E's bleedin' demised !