python - 为什么在 args 中使用一个参数时函数的结果不同？

Question

当我在 args 中传递 1 个参数时，它返回/打印元组中的参数和逗号。但是为什么不在 2 个或更多参数后添加逗号？

def print_args(*args):
    print(args)

#If arguments are more than one or zero:

print_args(1,2,3)  #Out: (1,2,3)
print_args(1,2)    #Out: (1,2)
print_args()       #Out: ()

#If I pass 1 argurment:

print_args(1)      #Out: (1,)  ?
print_args("a")    #Out: ('a',)?
print_args([])     #Out: ([],) ?

#Using return statement instead of print():

def return_args(*args):
    return args

return_args(1,2) #Out: (1, 2)
return_args(1) #Out: (1,)

Answer 1

在单个项目周围添加括号与冗余分组相同，并且不会将对象创建为元组。来自 docs :

A special problem is the construction of tuples containing 0 or 1items: the syntax has some extra quirks to accommodate these. Emptytuples are constructed by an empty pair of parentheses; a tuple withone item is constructed by following a value with a comma (it is notsufficient to enclose a single value in parentheses).

docs最后评论说这个实现确实“丑陋，但有效”。