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See in the Language Reference. If the form *identifier is present, it is initialized to a tuple receiving any excess positional parameters, defaulting to the empty tuple. If the form **identifier is present, it is initialized to a new dictionary receiving any excess keyword arguments, defaulting to a new empty dictionary. Also, see . Assuming that one knows what positional and keyword arguments are, here are some examples: Example 1: # Excess keyword argument (python 3) example: def foo(a, b, c, **args): print("a = %s" % (a,)) print("b = %s" % (b,)) print("c = %s" % (c,)) print(args) foo(a="testa", d="excess", c="testc", b="testb", k="another_excess")As you can see in the above example, we only have parameters a, b, c in the signature of the foo function. Since d and k are not present, they are put into the args dictionary. The output of the program is: a = testa b = testb c = testc {'k': 'another_excess', 'd': 'excess'}Example 2: # Excess positional argument (python 3) example: def foo(a, b, c, *args): print("a = %s" % (a,)) print("b = %s" % (b,)) print("c = %s" % (c,)) print(args) foo("testa", "testb", "testc", "excess", "another_excess")Here, since we're testing positional arguments, the excess ones have to be on the end, and *args packs them into a tuple, so the output of this program is: a = testa b = testb c = testc ('excess', 'another_excess')You can also unpack a dictionary or a tuple into arguments of a function: def foo(a,b,c,**args): print("a=%s" % (a,)) print("b=%s" % (b,)) print("c=%s" % (c,)) print("args=%s" % (args,)) argdict = dict(a="testa", b="testb", c="testc", excessarg="string") foo(**argdict)Prints: a=testa b=testb c=testc args={'excessarg': 'string'}And def foo(a,b,c,*args): print("a=%s" % (a,)) print("b=%s" % (b,)) print("c=%s" % (c,)) print("args=%s" % (args,)) argtuple = ("testa","testb","testc","excess") foo(*argtuple)Prints: a=testa b=testb c=testc args=('excess',) (责任编辑：) |