[Tagging] default value for "oneway"

[Xavier Noria]

On Thu, Aug 28, 2014 at 10:39 PM, Peter Wendorff
<wendorff at uni-paderborn.de> wrote:

> No, it isn't.
> The interpretation of the database, and the meaning, restricted to the
> fact of the streets oneway-ness is the same, but no value at all does
> not say "this is no oneway street", it says nothing more than "we don't
> know if it's oneway or not".

That is the generic interpretation of a NULL value in programming (I
am a programmer), absence of value. But your contract is that unset
implies no for streets. So there you go. Got no value? I *have* to
assume no.

And since that's the case, the de facto usage pattern seems to be to
leave oneway unset. The database has millions of NULLs for which the
users mean an actual "no". They didn't bother, but it is NULL for no.

And that is a consequence of the design of the data model for that
attribute. If this was 0-day of OSM and the attribute had possible
values "one-way", "two-way", "reversible", with an active default of
"two-way" preselected in UIs, then you could in practice say NULL
means unknown.