Python: Lambda in Parameter List

Question

Is there a nice solution to do something like this lambda function in a parameter list?

timeout = None

[...]

 response = self.session.post(
        url=self.baseUrl,
        data=str(data),
        headers=headers,
        timeout=lambda: 0 if self.timeout is None else self.timeout
    )

I know it throws an exception. But is there a possible solution to do something like this?

Thanks

It's not clear what you are doing. That code by itself would not throw an exception, it's perfectly valid; but presumably the post method is not expecting a callable, so I don't understand why you are passing it one. Why can't you simply do timeout=0 if self.timeout is None else self.timeout? — Daniel Roseman
– Daniel Roseman, Commented Feb 9, 2015 at 12:33
Agree with @DanielRoseman. You don't seem to gain any advantage here using lambda. Is this your real code or just an example you're using for the question? — Eithos
– Eithos, Commented Feb 9, 2015 at 12:36
Thank you @DanielRoseman. It was just an example code. Of course i should do timeout=0 if self.timeout is None else self.timeout . I just was wondering if there is a possibility to use the return of a function in a parameterlist — J-H
– J-H, Commented Feb 9, 2015 at 12:41

John Hua · Accepted Answer · 2015-02-09 12:50:44Z

1

timeout = None

 response = self.session.post(
        url=self.baseUrl,
        data=str(data),
        headers=headers,
        timeout=(lambda: 0 if self.timeout is None else self.timeout)()
    )

It is just an inline function works with closures.

answered Feb 9, 2015 at 12:50

John Hua

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Comments

oxfn · Accepted Answer · 2015-02-09 12:46:05Z

0

If you define timeout as class variable, than it is something determining object's state. In case where you have to set initial value depending on some condition you can do one of folowing basic things:

Initialize it in __init__
Use @property decorator and define getter, which returns applicable value.

answered Feb 9, 2015 at 12:46

oxfn

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