Python可變長引數

可變長的引數元組必須在位置和預設引數之後，帶元組（或者非關鍵字可變長引數）的函式普遍的語法如下：

def
function_name
([formal_args,] *nkwargs):
"function_documentation_string"
function_body_suite

星號操作符之後的形參將作為元組傳遞給函式,元組儲存了所有傳遞給函式的」額外」的引數(匹配了所有位置和具名引數後剩餘的)。如果沒有給出額外的引數，元組為空。示例：

def
tuplevarargs
(arg1, arg2='defaultb', *therest):
'display regular args and non-keyword variable args'
print
'formal arg 1:', arg1
print
'formal arg 2:', arg2
for eachxtrarg in therest:
print
'another arg:', eachxtrarg
print
'*' * 20
tuplevarargs('abc')
tuplevarargs(23, 4.56)
tuplevarargs('abc', 123, 'xyz', 456.789)

輸出：

formal arg 1: abc formal arg 2: defaultb ******************** formal arg 1: 23 formal arg 2: 4.56 ******************** formal arg 1: abc formal arg 2: 123 another arg: xyz another arg: 456.789

********************

使用變數引數字典來應對額外關鍵字引數的函式定義的語法：

def
function_name
([formal_args,][*nkwargs,] **kwargs):
"function_documentation_string"
function_body_suite

關鍵字變數引數應該為函式定義的最後乙個引數，帶**。示例：

def
dictvarargs
(arg1, arg2='defaultb', **therest):
'display 2 regular args and keyword variable args'
print
'formal arg1:', arg1
print
'formal arg2:', arg2
for eachxtrarg in therest.keys():
print
'xtra arg %s: %s' % (eachxtrarg, str(therest[eachxtrarg]))
print
'*' * 20
dictvarargs(1220, 740.0, c='grail')
dictvarargs(arg2='tales', c=123, d='poe', arg1='mystery')
dictvarargs('one', d=10, e='zoo', men=('freud', 'gaudi'))

輸出：

formal arg1: 1220 formal arg2: 740.0 xtra arg c: grail ******************** formal arg1: mystery formal arg2: tales xtra arg c: 123 xtra arg d: poe ******************** formal arg1: one formal arg2: defaultb xtra arg men: ('freud', 'gaudi') xtra arg e: zoo xtra arg d: 10

********************

關鍵字和非關鍵字可變長引數都有可能用在同乙個函式中，只要關鍵字字典是最後乙個引數並且非關鍵字元組先於它之前出現，正如在如下例子中的一樣：

def
newfoo
(arg1, arg2, *nkwargs, **kwargs):
'display regular args and all variable args'
print
'arg1 is:', arg1
print
'arg2 is:', arg2
for eachnkw in nkwargs:
print
'additional non-keyword arg:', eachnkw
for eachkw in kwargs.keys():
print
"additional keyword arg '%s': %s" % (eachkw, kwargs[eachkw])
print
'*' * 20
#example 1
newfoo(10, 20, 30, 40, foo=50, bar=60)
#example 2
newfoo(2, 4, *(6, 8), **)
#example 3
atuple = (6, 7, 8)
adict = 
newfoo(1, 2, 3, x=4, y=5, *atuple, **adict)

輸出：

arg1 is: 10 arg2 is: 20 additional non-keyword arg: 30 additional non-keyword arg: 40 additional keyword arg 'foo': 50 additional keyword arg 'bar': 60 ******************** arg1 is: 2 arg2 is: 4 additional non-keyword arg: 6 additional non-keyword arg: 8 additional keyword arg 'foo': 10 additional keyword arg 'bar': 12 ******************** arg1 is: 1 arg2 is: 2 additional non-keyword arg: 3 additional non-keyword arg: 6 additional non-keyword arg: 7 additional non-keyword arg: 8 additional keyword arg 'y': 5 additional keyword arg 'x': 4 additional keyword arg 'z': 9

********************

說明：

Python可變長引數

python可變長引數

python 可變長引數

python變長引數列表可變長引數

Python可變長引數

python可變長引數

python 可變長引數

python變長引數列表 可變長引數

相關推薦

python變長引數列表可變長引數