Ternary operator alternative in Ptyhon
Robert Lehmann
stargaming at gmail.com
Wed Jun 18 02:27:33 EDT 2008
On Tue, 17 Jun 2008 23:18:51 -0700, kretik wrote:
> I'm sure this is a popular one, but after Googling for a while I
> couldn't figure out how to pull this off.
>
> Let's say I have this initializer on a class:
>
> def __init__(self, **params):
Why not ``__init__(self, mykey=None)`` in the first place?
> I'd like to short-circuit the assignment of class field values passed in
> this dictionary to something like this:
>
> self.SomeField = \
> params.has_key("mykey") ? params["mykey"] : None)
>
> Obviously I know this is not actual Python syntax, but what would be the
> equivalent? I'm trying to avoid this, basically:
>
> if params.has_key("mykey"):
> self.SomeField = params["mykey"]
> else:
> self.SomeField = None
>
> This is not a big deal of course, but I guess my main goal is to try and
> figure out of I'm not missing something more esoteric in the language
> that lets me do this.
>
> Thanks in advance.
You're lucky -- Python 2.5 just grew a ternary if-construct. You'd use it
like that::
self.SomeField = params["mykey"] if "mykey" in params else None
# or, generically: TRUE if CONDITION else FALSE
Notice the use of the `in` operator, which is recommended over
`dict.has_key`.
HTH,
--
Robert "Stargaming" Lehmann
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