具有多个参数的函数**args

Question

我正在学习python,这是来自

http://www.learnpython.org/page/MultipleFunctionArguments

他们有一个不起作用的示例代码 - 我想知道它是否只是一个错字或者根本不应该工作.

def bar(first, second, third, **options):
    if options.get("action") == "sum":
        print "The sum is: %d" % (first + second + third)

    if options.get("return") == "first":
        return first

result = bar(1, 2, 3, action = "sum", return = "first")
print "Result: %d" % result

Learnpython认为输出应该是 -

The sum is: 6
Result: 1

我得到的错误是 -

Traceback (most recent call last):
  File "/base/data/home/apps/s~learnpythonjail/1.354953192642593048/main.py", line 99, in post
    exec(cmd, safe_globals)
  File "<string>", line 9
     result = bar(1, 2, 3, action = "sum", return = "first")
                                                ^
 SyntaxError: invalid syntax

有没有办法做他们想要做的事情或者示例错了？对不起,我确实看过有人回答的python教程,但我不明白如何解决这个问题.

Answer 1

return是python中的关键字 - 您不能将其用作变量名.如果你把它改成别的东西(例如ret)它会正常工作.

def bar(first, second, third, **options):
    if options.get("action") == "sum":
        print "The sum is: %d" % (first + second + third)

    if options.get("ret") == "first":
        return first

result = bar(1, 2, 3, action = "sum", ret = "first")
print "Result: %d" % result