python - 为什么元组用括号括起来？

Question

a tuple is a comma-separated list of values

所以声明元组的有效语法是:

tup = 'a', 'b', 'c', 'd'

但是我经常看到的是这样的声明:

tup = ('a', 'b', 'c', 'd')

将元组括在圆括号中有什么好处？

Answer 1

来自Python docs :

... so that nested tuples are interpreted correctly. Tuples may be input with or without surrounding parentheses, although often parentheses are necessary anyway (if the tuple is part of a larger expression).

嵌套元组的例子:

tuple = ('a', ('b', 'c'), 'd')