Python lambda不接受元组参数 [英] Python lambda does not accept tuple argument

问题描述

我正在两台PC上运行带有PyDev v2.6插件的Eclipse SDK v3.6，带有Linux和Windows。

I am running Eclipse SDK v3.6 with PyDev v2.6 plugin on two PC, with Linux and Windows.

我想通过一个元组作为参数，如（例如）：

I would like to pass a tuple as an argument, like (just example):

foo = lambda (x,y): (y,x)
print (foo((1,2)))

这个工作在Linux上，并给出结果： / p>

This works on Linux and gives the result:

（2,1）

(2,1)

在Windows上它会引发错误：

On Windows it rises an error:

foo = lambda (x,y): (y,x)
             ^
SyntaxError: invalid syntax

如何解决问题？
提前感谢...

How to solve the problem? Thanks in advance...

感谢 interjay 及其对 PEP 3113 我发现一个元组参数从3.0版本的Python中弃用。

Thanks to interjay and his reference to PEP 3113 I found that a tuple parameter is deprecated from 3.0 version of Python.

所以，没有工作，看起来像

So, the code which did not worked and looked as

accepts = filter(lambda q1, q2: (q1, q2) in states, [(q1, q2) for q1 in D1.accepts for q2 in D2.accepts])

现在适用于版本2.7和版本3.0的Python并且看起来像

now works on both version 2.7 and version 3.0 of Python and looks as

accepts = filter(lambda q: (q1, q2) in states, [(q1, q2) for q1 in D1.accepts for q2 in D2.accepts])

其中接受

推荐答案

您可能在Windows上运行Python 3.x，在Linux上运行Python 2.x 。在Python 3中删除了解包元组参数的功能：请参阅 PEP 3113 。

You are probably running Python 3.x on Windows, and Python 2.x on Linux. The ability to unpack tuple parameters was removed in Python 3: See PEP 3113.

您可以手动解压缩元组，这对Python 2.x和3.x都有效：

You can manually unpack the tuple instead, which would work on both Python 2.x and 3.x:

foo = lambda xy: (xy[1],xy[0])

或者：

def foo(xy):
    x,y = xy
    return (y,x)

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