JavaScript's void operator in Python?
Jon Ribbens
jon+usenet at unequivocal.eu
Sun Feb 2 18:29:47 EST 2020
On 2020-02-02, Stefan Ram <ram at zedat.fu-berlin.de> wrote:
> Jon Ribbens <jon+usenet at unequivocal.eu> writes:
>>Why does it matter if the return value is None?
>
> In a lambda, a return value of None sometimes would be
> convenient as by convention it indicates that the return
> value does not carry any information and the function is
> intended to be used just for its effect. A value of None
> will not be printed in the console, so it does not add
> distracting noise there.
If it's a lambda then the arguments will be evaluated before the
lambda is called anyway, so:
>>> f = lambda *x: None
>>> f(print(2), print(3))
2
3
Or if you're writing it inline then:
>>> (None, print(2), print(3))[0]
2
3
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