function with multiple arguments **args

Question

I am learning python and this is from

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

They have an example code that does not work- I am wondering if it is just a typo or if it should not work at all.

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 thinks the output should have been-

The sum is: 6
Result: 1

The error i get is-

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

Is there a way to do what they are trying to do or is the example wrong? Sorry I did look at the python tutorial someone had answered but I don't understand how to fix this.

Answer 1

return is a keyword in python - you can't use it as a variable name. If you change it to something else (eg ret ) it will work fine.

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

Answer 2

您可能不应使用“ return ”作为参数名称，因为它是Python命令。