Return value if the value is true in python

Question

I want to the return the value of the statement if it evaluates to true. For example,

if f():
   return f()
elif g():
   return g()

The function may return a list also. since empty list evaluates to false, is there a better way to do it. I don't want to store the value outside the scope of the if statement.

I don't understand what you're asking. What do you want to happen with an empty list? And why don't you want to store the value? — Daniel Roseman
– Daniel Roseman, Commented Apr 25, 2019 at 12:41
If you want to return f() if it is truthy (otherwise g()), then you could use return f() or g(). The information in your question is not very clear. — khelwood
– khelwood, Commented Apr 25, 2019 at 12:45
@khelwood This is true unless you don't want to return neither of f() or g() if they are not truthy (e.g. if neither of these things are true then I have to do some more work). — javidcf
– javidcf, Commented Apr 25, 2019 at 12:50
@khelwood your answer works good but the syntactically I was expecting something like jdehesa's answer. This is available in C++, I thought there would be a similar functionality in python. — Pradeep Kumar
– Pradeep Kumar, Commented Apr 25, 2019 at 12:59
@DanielRoseman I don't want to return an empty list that is why I have if checks — Pradeep Kumar
– Pradeep Kumar, Commented Apr 25, 2019 at 13:01

javidcf · Accepted Answer · 2019-04-25 12:43:46Z

3

Currently you can only do:

out = f()
if out: return out
out = g()
if out: return out

But maybe what you are thinking of is something like the (controversial) assignment expressions coming up in Python 3.8. With this you will be able to do:

if out := f():
    return out
elif out := g():
    return out

answered Apr 25, 2019 at 12:43

javidcf

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