python 關鍵參數(shù)

如果某個函數(shù)有很多參數(shù)，而現(xiàn)在只想指定其中的部分，那么可以通過命名為這些參數(shù)賦值（稱為‘關鍵參數(shù)’）。

優(yōu)點：不必擔心參數(shù)的順序，使函數(shù)變的更加簡單；假設其他參數(shù)都有默認值，可以只給我們想要的那些參數(shù)賦值。

def func(a, b=2, c=3):

    print "a is %s, b is %s, c is %s" % (a, b, c)

func(1) #a is 1, b is 2, c is 3

func(1, 5) #a is 1, b is 5, c is 3

func(1, c = 10) #a is 1, b is 2, c is 10

func(c = 20, a = 30) #a is 30, b is 2, c is 20