Python conditional variable assignment

Question

Morning all,

Can someone advise, is it possible to achieve something like this:

def myFunction(someParam)
   if someParam == 1:
      return "This and that"
   else:
      return None

someVariable = someVariable || myFunction(valuePassedIn)

ie, given "someVariable" has an existing value, I want to preserve that value, or replace it with the value returned from "myFunction", provided that is not None?

Obviously, I can do something like:

if myFunction(valuePassedIn) != None:
    someVariable = myFunction(valuePassedIn)

But this of course is calling myFunction twice. Alternatively, I could do:

myFuncRes = myFunction(valuePassedIn)
if MyFuncRes != None:
    someVariable = myFuncRes

But it'd be good if I could reduce this to a single line of code, as per my "||" line in the first code snippet above. Obviously I've seen the conditional expressions documentation, but unless I'm misunderstanding, this would still involve calling myFunction twice?

I guess one other option would be to pass someVariable in as an additional param to myFunction and use this as the "else" return instead of None, but I can't help feeling this is kinda messy - and Python probably has something more slick I could use?

Thanks

Note that if someParam = 1 in your myFunction is actually doing an assignment, not a comparison. — Wieland
– Wieland, Commented Nov 28, 2014 at 9:31

NPatel · Accepted Answer · 2014-11-28 09:21:20Z

4

Yes you can do this

Please check below code

>>> a = 1
>>> def test(b):
...     return b*10
...
>>> c = a or test(2)
>>> c
1
>>> a = 0
>>> c = a or test(2)
>>> c
20

answered Nov 28, 2014 at 9:21

NPatel

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