python显式没有传递可选参数
作者:互联网
想象一下以下场景:
class A:
def __init__(self, arg1=3, arg2=5):
pass
def createA(arg1=None, arg2=None):
if arg1 is None:
if arg2 is None:
a = A()
else:
a = A(arg2=arg2)
else:
if arg2 is None:
a = A(arg1=arg1)
else:
a = A(arg1=arg1, arg2=arg2)
return a
什么是实现此行为的最佳方式,请注意以下事项:
>我不能/不想改变A级
>我不想显式地将A的构造函数参数的默认值添加到createA函数中?
例如,是否有任何值表示未通过可选参数?
就像是:
if arg1 is None:
newArg1 = NotPassed
else:
newArg1 = arg1
if arg2 is None:
newArg2 = NotPassed
else:
newArg2 = arg2
A(arg1=newArg1, arg2=newArg2)
解决方法:
def create_A(arg1=None, arg2=None):
kwargs = {}
if arg1 is not None: kwargs['arg1'] = arg1
if arg1 is not None: kwargs['arg2'] = arg2
return A(**kwargs)
或者甚至是
def create_A(**kwargs):
return A(**kwargs)
标签:python,optional-parameters 来源: https://codeday.me/bug/20190725/1537044.html