On Mar 18, 7:52 pm, "Gabriel Genellina" <[EMAIL PROTECTED]>
wrote:
> def f(*args, **kw):
>
> ... print "args",args
> ... print "kw",kw
> ...>>> d = {"a":1, "b":2, "c":3}
> >>> f(**d)
>
Whoa! **? And applied to a function parameter? Back to the drawing
board.
On Mar 18, 7:21 pm, [EMAIL PROTECTED] (Alex Martelli) wrote:
> More generally, with any iterable x, the *x
> construct in function call will pass as positional arguments exactly
> those items which (e.g.) would be printed by the loop:
> for item in x: print x
>
Thanks.
On Mar 18, 7:52 pm, "Gabriel Genellina" <[EMAIL PROTECTED]>
wrote:
> def f(*args, **kw):
>
> ... print "args",args
> ... print "kw",kw
> ...>>> d = {"a":1, "b":2, "c":3}
> >>> f(**d)
>
Whoa! **? And applied to a function parameter name? Back to the
drawing board.
The following is what I discovered for anyone else that is interested:
More on Defining Functions(GvR tutorial, section 4.7)
--Keyword Argument Lists
--Arbitrary Argument Lists
--Unpacking Argument Lists
1) Applying ** to a function parameter:
def g(a, b, **xtraArgs):
print xtraArgs
g(b=20, c="big", a="hello", d=10)
#output: {'c': 'big', 'd': 10}
**xtraArgs will be a dictionary of all arguments sent to the function
with the syntax "keyword=value" if the keyword does not match any of
the function parameter names.
2)Applying * to a function parameter:
def g(a, *xtraArgs):
print xtraArgs
g(10, 20, 30, 40)
#output: (20, 30, 40)
*xtraArgs will be a tuple containing all arguments sent to the
function with the syntax "value" that do not match any function
parameter.
3) A function parameter with the syntax *xtraArgs1 must come before a
function parameter with the syntax **xtraArgs2:
def g(a, b, *xtraArgs1, **xtraArgs2):
print xtraArgs1
print xtraArgs2
g(10, 20, 30, 35, d=40, e="hello")
#(30, 35)
#{'e': 'hello', 'd': 40}
4) Using * to unpack a list, tuple, etc.(any iterable collection--see
earlier posts):
def g(a, b, c):
print a,b,c
tpl = (1, 2, 3)
g(*tpl)
#output: 1 2 3
5) Using ** to unpack dictionaries:
def g(a, b, c):
print a,b,c
dict = {"b":"world", "c":"goodbye", "a":"hello"}
g(**dict)
#output: hello world goodbye
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