On 9 May 2008, at 12:21, Dave Stubbs wrote:
The mapping to numbers doesn't gain us anything. It doesn't let us do
anything we can't already do, or make it any easier as far as I can
see.
If the database, which is accessed by programmers, was numerically
based, it would be be more amenable to algorithmic logic. At the
simplest level, selecting elements with values above/below certain
levels. The numbers would of course have to follow some logical
pattern. Similar procedures using the current tags involve clumsier
code like 'motorway OR trunk OR primary' and, if users are actually
typing these words in (rather than selecting from human-friendly
menus presented by the editor) a typo such as 'secodnary' cold
corrupt the database and prevent the feature being seen by map
viewers or routing engines for example.
I think you were actually suggesting something like "type=11" -- where
10-20 means roads, 30-40 could mean railways etc. But as far as this
argument goes it doesn't really make much difference, other than
leaving us with a massive allocation problem which has been neatly
sidestepped by using free-form tagging.
Yes free-form tagging avoids having to decide on a pattern and allows
for open-ended evolution, but it doesn't work if it's completely free-
form. I could describe many roads around here as 'highway=country
lane" but would they get rendered? The fact that there are tagging
recommendations acknowledges that anarchy would not work. But a data
structure would have to allow change and evolution (at the simplest
level, leaving spare numbers for future use) and this is a challenge.
Indeed point missed again.
We DON'T DO (sorry Richard) highway=red. We do highway=primary and you
can make that any colour you like... same as you can do with
highway=13/type=13 -- it makes no difference is my point. Numbering
the highways won't help.
Now I'm confused. I'm not suggesting numbers to avoid red highways
for goodness' sake!
It could yes. There are a couple of issues with this mostly to do with
actually maintaining the style sheets and providing the processing
power/disk space.
Moore's Law should take care of those :-)
No problemo! Special viewers like the cycle map would simply apply
their own
filters. And with well-structured data a map viewer could even
have settings
(eg. cycle routes on/off) allowing it to be customised by the
user, making a
proliferation of specialist viewers unnecessary.
Hmm.. yes, maybe. But the point of your e-mail was essentially
numbering everything, and that really doesn't help us with this goal.
It's just that numbers are easier for programmers (see above). Users
would never see them. They would see words in their own language and
the viewer/editor would map words to numbers.
elvin
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