如何处理有时未使用的函数参数?

How to deal with sometimes unused arguments of function?

你能告诉我如何处理有时未使用的函数参数吗?提前致谢!

函数:

def foo(a, b=2, c="default"):
  print(c)
  return a + b

用法:

arg_1 = int(input())
if arg_1 == 2:
  arg_2 = 3
  arg_3 = "using 3"
else:
  # what can I do here?
  arg_2 = *universal_value_that_is_disabling_argument
  arg_3 = *universal_value_that_is_disabling_argument
  # I know that I can use arg_2 = 2 and arg_3 = "default", 
  # but it is not really convenient when there are many arguments

foo(arg_1, b=arg_2, c=arg_3)

我知道我可以做这样的事情,但是当参数很多时不太方便:

arg_1 = int(input())
if arg_1 == 2:
  foo(arg_1, 3, "using 3")
else:
  foo(arg_1)

通过解包命名参数的字典来调用它。然后你可以简单地省略应该获得默认值的参数。

if arg_1 == 2:
    options = {'b': 3, 'c': 'using 3'}
else:
    options = {}

foo(arg_1, **options)