*Memos:
- My post explains parameters and arguments.
- My post explains iterable unpacking in variable assignment.
-
My post explains
*for iterable unpacking in variable assignment. -
My post explains
**for dictionary unpacking. -
My post explains
*argsand**kwargsin function.
You can use * for a function parameter and argument for iterable unpacking as shown below:
*Memos:
- A
*is an iterable unpacking operator. - A function can have only one
*parameterwhich is*argsconventionally. *A*parameteris a var-positional parameter. - A
*parametercan store zero or more values as a tuple. - A
*parametercannot have a default value. - Zero or more
*iterablescan be used as the arguments passed to the zero or more parameters including a*argsand**kwargs.
def func(*args): pass
def func(*mylist): pass
def func(p, *args): pass
def func(p="param", *args): pass
def func(*args, p): pass
def func(*args, p="param"): pass
def func(*args, **kwargs): pass
def func(p, *args, **kwargs): pass
def func(p="param", *args, **kwargs): pass
def func(*args, p, **kwargs): pass
def func(*args, p="param", **kwargs): pass
# No error
def func(*args1, *args2): pass
# SyntaxError: * argument may appear only once
def func(**kwargs, *args): pass
# SyntaxError: arguments cannot follow var-keyword argument
def func(*args=["John"]): pass
def func(*args=*["John"]): pass
# SyntaxError: var-positional argument cannot have default value
def func(*args):
print(args, *args)
func()
func(*[])
func(*())
func(*{})
func(**{})
# () Nothing
func({})
# ({},) {}
func(0)
func(*[0])
func(*(0,))
# (0,) 0
func(0, 1)
func(*[0, 1])
func(*(0, 1))
# (0, 1) 0 1
func(0, 1, 2)
func(*[0, 1, 2])
func(*(0, 1, 2))
# (0, 1, 2) 0 1 2
func(0, 1, 2, 3)
func(*[0, 1, 2, 3])
func(*(0, 1, 2, 3))
# (0, 1, 2, 3) 0 1 2 3
func(0, 1, 2, 3, 4)
func(*[0, 1, 2, 3, 4])
func(*(0, 1, 2, 3, 4))
# (0, 1, 2, 3, 4) 0 1 2 3 4
func([])
# ([],) []
func([0])
# ([0],) [0]
func([0, 1])
# ([0, 1],) [0, 1]
func([0, 1, 2])
# ([0, 1, 2],) [0, 1, 2]
func([0, 1, 2, 3])
# ([0, 1, 2, 3],) [0, 1, 2, 3]
func([0, 1, 2, 3, 4])
# ([0, 1, 2, 3, 4],) [0, 1, 2, 3, 4]
func(())
# ((),) ()
func((0,))
# ((0,),) (0,)
func((0, 1))
# ((0, 1),) (0, 1)
func((0, 1, 2))
# ((0, 1, 2),) (0, 1, 2)
func((0, 1, 2, 3))
# ((0, 1, 2, 3),) (0, 1, 2, 3)
func((0, 1, 2, 3, 4))
# ((0, 1, 2, 3, 4),) (0, 1, 2, 3, 4)
func({"fname":"John", "lname":"Smith"})
# ({'fname': 'John', 'lname': 'Smith'},) {'fname': 'John', 'lname': 'Smith'}
func({"fname":"John"}, {"lname":"Smith"})
# ({'fname': 'John'}, {'lname': 'Smith'}) {'fname': 'John'} {'lname': 'Smith'}
func(*{"fname":"John", "lname":"Smith"})
func(*{"fname":"John"}, *{"lname":"Smith"})
# ('fname', 'lname') fname lname
def func(p1="p1", p2="p2", *args, p3="p3"):
print(p1, p2, args, p3)
func()
func(*[])
func(*())
func(*{})
func(**{})
# p1 p2 () p3
func({})
# {} p2 () p3
func(0)
func(*[0])
func(*(0,))
# 0 p2 () p3
func(0, 1)
func(*[0, 1])
func(*(0, 1))0 1 () p3
# 0 1 () p3
func(0, 1, 2)
func(*[0, 1, 2])
func(*(0, 1, 2))
# 0 1 (2,) p3
func(0, 1, 2, 3)
func(*[0, 1, 2, 3])
func(*(0, 1, 2, 3))
# 0 1 (2, 3) p3
func(0, 1, 2, 3, 4)
func(*[0, 1, 2, 3, 4])
func(*(0, 1, 2, 3, 4))
# 0 1 (2, 3, 4) p3
func([])
# [] p2 () p3
func([0])
# [0] p2 () p3
func([0, 1])
# [0, 1] p2 () p3
func([0, 1, 2])
# [0, 1, 2] p2 () p3
func([0, 1, 2, 3])
# [0, 1, 2, 3] p2 () p3
func([0, 1, 2, 3, 4])
# [0, 1, 2, 3, 4] p2 () p3
func(())
# () p2 () p3
func((0,))
# (0,) p2 () p3
func((0, 1))
# (0, 1) p2 () p3
func((0, 1, 2))
# (0, 1, 2) p2 () p3
func((0, 1, 2, 3))
# (0, 1, 2, 3) p2 () p3
func((0, 1, 2, 3, 4))
# (0, 1, 2, 3, 4) p2 () p3
func({"fname":"John", "lname":"Smith"})
# {'fname': 'John', 'lname': 'Smith'} p2 () p3
func({"fname":"John"}, {"lname":"Smith"})
# {'fname': 'John'} {'lname': 'Smith'} () p3
func(*{"fname":"John", "lname":"Smith"})
func(*{"fname":"John"}, *{"lname":"Smith"})
# fname lname () p3
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