[OSM-talk] turn restriction relations: via

[Tobias Knerr]

Nic Roets wrote:
> I implemented "only_*" as something that's disallowed i.e. a restriction.
> The "obligation" interpretation only came later.
> 
> Perhaps we can specify that complex vias may not have "only_*"'s and require
> people to implement their ideas with no_'s ?

While I don't see a problem with this requirement in theory, I doubt
that the idea would be a very popular, partly because the traffic signs
(rendering hints) and the relation semantics have been merged by using
that strange only_/no_-prefix solution.

>> Despite via splitting not being necessary for proper relation handling,
>> I still think that "a relation using via nodes will always contain all
>> nodes as via nodes one would travel along" is essential. Otherwise,
>> there would inevitably be some problems:
>> If, in your example, the via information was represented by via nodes on
>> S instead of via way(s), that restriction would also forbid turning left
>> from A onto S, following S without turning into B, then using other
>> roads to return to the double carriageway and following B back to the
>> restriction's "to" part. This is obviously not intended.
> 
> I think we should require that complex vias must always include all the ways
> that are traveled.

Does "way" mean way primitives here, as opposed to nodes?

Tobias Knerr