[Talk-GB] Vandalism in London

[Frederik Ramm]

Hi,

On 10/05/2014 01:35 AM, David Woolley wrote:
> Note that both of them fix up the relations, by removing the member, so
> the relation is never structurally invalid

The API would not allow deleting a way that is still member of a
relation, so relations will (barring API bugs) always be structurally
valid, no matter how braindead an editor is.

> I think iD has taken totally the wrong approach.  If the concept is too
> difficult for the target audience, it should have refused the operation,
> rather than hidden the problem.

I can see both sides.

If you want to delete something for a legitimate reason - meaning:
because it just isn't there on the ground - then why should you care in
how many relations it is - if it isn't there then it ought to be
deleted, period, and you'll be thankful if the editor takes care of
ensuring referential integrity of relations for you.

Difficulties arise when you delete something in error (then of course
pointing out to you how big the effect of your change is would
potentially make you rethink), or when you delete something with the
plan of re-drawing it. This is not something that an experienced mapper
would normally do - they would just improve the object that's there. But
newbies who think "drawing program" when they use an OSM editor are more
prone to deleting something and re-creating it. In that case, making the
user aware that they'll have to put the newly created thing back into
all these relations might discourage them from making that edit. A
relation saved, but an improvement lost...

JOSM has a plugin that will let you make a "replace geometry" operation.
You draw your new thing, then order JOSM to replace the geometry of the
old thing by what you've just drawn, and JOSM attempts to retain the
history and tags and relation memberships of the old object. But that,
again, is a very advanced operation that will be difficult to sell to a
newbie.

Bye
Frederik

-- 
Frederik Ramm  ##  eMail frederik at remote.org  ##  N49°00'09" E008°23'33"