Feature and Improvement Requests for TAPRegExt 1.1

Note: TAPRegExt is currently being worked on in after TAP went to 1.1.

Variadic Functions

It looks like we will have quite a few use-defined functions with a variable number of arguments (for instance, coordinate transformations which might accepts both geometries and split coordiates).

Current TAPRegExt function signatures don't support this (ok, they're only loosely defined in the first place, but libraries actually try to parse them).

What should we do? Just have one feature per variation? Might be rather verbose. Have some EBNF-inspired syntax for optional arguments? That's a bit on the complex side when the things are actually parsed. Anything else?