On Mon, May 25, 2020 at 3:42 AM David Mertz <[email protected]> wrote:
> The pattern:
>
> def fun(..., option=None):
> if option is None:
> option = something_else
>
> Becomes second nature very quickly. Once you learn it, you know it. A line
> of two of code isn't a big deal.
>
And it isn't entirely correct, because now None isn't a valid
parameter. It's an extremely common idiom right up until it doesn't
work, and you need:
_SENTINEL = object()
def fun(..., option=_SENTINEL):
if option is _SENTINEL:
option = something_else
Now, try doing that for multiple parameters at once. Or in a closure.
Or anything else that would make it more complicated.
ChrisA
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