如果字符是个开括号，把它压入堆栈。

If the character is an opening parenthesis, push it onto the stack.

youdao

开括号后面跟着一个可选的参数列表。

The open-parenthesis is followed by an optional argument list.

youdao

不可以用操作符、函数、逗号或开括号作为表达式结束符。

Expressions must not end with an operator, function, comma, or opening parenthesis.

youdao

Well at some level it is an ordered sequence of characters. Right? Now it is not represented this same way. You don't see strings inside these open parens and closed parens.

现在字符串不是用这种方式表达的,你没有看到字符串里有开括号闭括号,字符串中间也没有逗号,但是它有同样的属性。

麻省理工公开课 - 计算机科学及编程导论课程节选

It says, if I want to print out something I built in Cartesian form up here, says, again, I'm going to pass it in a pointer to the instance, that self thing, and then I'm going to return a string that I combine together with an open self and close paren, a comma in the middle, and getting the x-value and the y-value and converting them into strings before I put the whole thing together.

这不仅仅是个列表,它是怎么来做的？,流程是：如果我想要返回,一些已经在笛卡尔模式下建好的值，好，再说一遍，我首先要传入一个,指向实例的指针,也就是，然后我会返回一个,由开括号，闭括号,中间的一个逗号,以及提前转换为字符串格式的。

麻省理工公开课 - 计算机科学及编程导论课程节选