Question

Python希望在参数列表的末尾使用任意参数，但是如果我们拥有默认参数并为其分配了值，则在此之前。如何传递参数以匹配参数。问题是，不必为sales_man参数传递参数，并且必须打印未知参数。

  def pizzas(size, sales_man='unknown', *toppings):
         print(f'your order is accepted for the pizza size: {size} by {sales_man}'
               f'\nPlease check your toppings as below: ')
         for topping in toppings:
             print(f'- {topping}')


     pizzas('medium', 'cheesy', 'Bacon', 'pepporni', 'Pineapple')

Answer 1

将def更改为：

def pizzas(size, *toppings, sales_man='unknown')

然后sales_man可以作为关键字参数而不是位置参数传递：

pizzas('medium', 'cheesy', 'Bacon', 'pepporni', 'Pineapple')

输出：

your order is accepted for the pizza size: medium by unknown
Please check your toppings as below: 
- cheesy
- Bacon
- pepporni
- Pineapple

输入：

pizzas('medium', 'cheesy', 'Bacon', 'pepporni', 'Pineapple', sales_man="Man")

输出：

your order is accepted for the pizza size: medium by Man(...)

Answer 2

您只是不能这样做。每次调用该函数时，都必须提供该默认值（这违背了使用默认值开头的目的），或者将默认参数移到定义的末尾，并在调用中明确提及它，如下所示：

def a(b, *c, d=5):
    ...

a(1, 2,3,4,5, d=6)

Answer 3

您只是不能这样做。相反，您可以尝试---

def pizzas(size, sales_man, *toppings):
  if sales_man == None:
    sales_man = 'unknown'
  print("sales_man :: " + sales_man)
  print(f'your order is accepted for the pizza size: {size} by {sales_man}'f'\nPlease check your toppings as below: ')
  for topping in toppings:
    print(f'- {topping}')

pizzas('medium', None, 'cheesy', 'Bacon', 'pepporni', 'Pineapple')

或

将方法签名更改为--- def pizzas(size, *toppings, sales_man='unknown'):

如果您想通过 sales_man ，则可以将其称为

pizzas('medium','cheesy', 'Bacon', 'pepporni', 'Pineapple', sales_man="Pawan")

或者如果您不想通过 sales_man ，则可以将其称为

pizzas('medium','cheesy', 'Bacon', 'pepporni', 'Pineapple')

如何用任意参数对默认参数排序

3 个答案: