Diez B. Roggisch wrote:
> Bjoern Schliessmann schrieb:
>> mario ruggier wrote:
>>
>>> It may sometimes be useful to make use of the conceptual
>>> difference between these two cases, that is that in one case the
>>> user did not specify any key and in the other the user explicitly
>>> specified the key to be None.
>> Do you have an example where this might be useful?
>
> Any situation in which there would otherwise lots of documentation
> needed to inform the user that the sentinel value is something else than
> None.
>
> Take something like this as an example:
>
> def update_user(some, values, nullable_value=sentinel):
> # first, work with some and values
> ...
> # then, on something actually being passed to nullable_value
> if nullable_value is not sentinel:
> connection.cursor().execute("update table set value = ?",
> nullable_value)
>
>
>
> I've seen this before, in code from e.g. Alex Martelli.
>
Sure, but the OP's question was "Is there any way to tell between
whether a keyword arg has been explicitly specified (to the same value
as the default for it)". We've drifted a long way from that, since the
code you demonstrate doesn't detect an explicit call with
nullable_value==sentinel -- the reason being, I submit, that there is no
use case for such code.
regards
Steve
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