Examples showing the flexibility of passing args and kwargs to python functions.

test_kwargs.py

import sys
num = 0
def printNum(func):
    def pprint(*args, **kwargs):
        global num
        num += 1
        sys.stdout.write(u'%s: ' % num)
        sys.stdout.write(func(*args, **kwargs))
        sys.stdout.write(u'\n')
    return pprint

@printNum
def func1(a, b, c, d):
    return "%s, %s, %s, %s" % (a, b, c, d)

@printNum
def func2(a, b, c, d=4):
    return "%s, %s, %s, %s" % (a, b, c, d)


# 1. Pass in as positional arguments
func1(1, 2, 3, 4)

# 2. Pass in as named kw arguments
func1(d=4, c=3, b=2, a=1)

# 3. This is the same as passing in named kw arguments
func1(**dict(a=1, b=2, c=3, d=4))

# 4. This is the same as passing in named kw arguments
func1(**{ 'a': 1, 'b': 2, 'c': 3, 'd': 4 })

# 5. You can mix positional and kwargs
func1(1, 2, d=4, c=3)

# 6. This isthe same as the signature above
func1(1,2,**{ 'c': 3, 'd': 4 })

# 7. You cannot pass the value for a formal parameter as both a positional argument and a kwargument
try:
    func1(4,3,**{ 'a': 1, 'b': 2, 'c': 3, 'd': 4 })
except TypeError:
    print "TypeError: func1() got multiple values for keyword argument 'a'"

# 7. Functions with default values can be passed values as a positional argument
func2(1, 2, 3, 4)

# 8. Functions with default values can be passed values as kwargs
func2(d=4, c=3, b=2, a=1)

# 9. Functions with default values can be left off completly
func2(1, 2, 3)
func2(c=3, b=2, a=1)