Checking whether type is None
Stephan Houben
stephanh42 at gmail.com.invalid
Wed Jul 25 10:20:05 EDT 2018
Op 2018-07-24, Chris Angelico schreef <rosuav at gmail.com>:
> On Wed, Jul 25, 2018 at 9:18 AM, Rob Gaddi
><rgaddi at highlandtechnology.invalid> wrote:
>> On 07/24/2018 01:07 PM, Chris Angelico wrote:
>> I suppose one valid usage would be this sort of thing:
>>
>> fn = {
>> int: dispatchInt,
>> str: dispatchStr,
>> list: dispatchList,
>> type(None): dispatchNone
>> }[type(x)]
>> fn(x)
>>
>
> True, but that would be useful only in a very few situations, where
> you guarantee that you'll never get any subclasses. So if you're
> walking something that was decoded from JSON, and you know for certain
> that you'll only ever get those types (add float to the list and it's
> basically covered), then yes, you might do this; and then I would say
> that using "type(None)" is the correct spelling of it.
This is actual code I have:
@singledispatch
def as_color(color):
"""Convert object to QColor."""
return QtGui.QColor(color)
as_color.register(type(None), lambda x: QtGui.QColor(0, 0, 0, 0))
Stephan
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