SODA Gripes (5) No single-value arguments for intervals

[Markus Demleitner]

Dear DAL,

I trust you've all been looking forward to it: here's the next
installement in the series on SODA gripes (but this one is short and
relatively straightforward).  

This is about the following regulation in the current Draft

  "If there is one single value the interval is assumed to be
  infinitely small (a scalar value)."

(e.g., on BAND, but it seems to be intended as a general rule).
Essentially, by this rule,

BAND=550

would be equivalent to

BAND=550 550

I propose to strike this rule.  

It does not add new capabilities but is a significant pain in
implementation, since you'll somehow have to teach your VOTable
tabledata parser to suddenly accept a single value into a 2-array
(and really, what should it put into the second element of that
2-array? NULL?  Please not, remember there's integers, too).

And even if single values weren't a big pain:

$ python -c "import this" | grep preferably
There should be one-- and preferably only one --obvious way to do it.

Cheers,

           Markus


For bookkeeping, here's the current state of my series of gripes,
unnumbered means "you can still look forward to it".  The names in
parenthesis in case of unresolved items are the persons that more or
less promised to get back to these issues:

(1) The big one (François)
(2) No gratuitous xtypes (OK)
(3) In-DAL SODA descriptor optional, introductory text (François)
(4) Mandated multiplicities considered harmful (Pat)
(5) No single-value arguments for intervals (everyone)
() @value and @ref semantics documented for PARAMs
() Spatial coverage discovery and the RA and DEC parameters
() Pixel coutouts: PIXEL_n
() Behaviour for no-ID queries?  For queries with only ID?
() POS doesn't have an xtype
() Examples stuff: example example, and perhaps a dl-id term?