On Sat, Jul 01, 2006 at 10:58:05AM -0400, Andrew Dunstan wrote: > Tom Lane wrote: > > >The output function, however, would be quite a trick. > >It's not going to receive anything except the Datum itself. > > I understand the reasons for this limitation of output functions, but I > have now seen it bite several times. Maybe we need a little out of the > box thinking on this. I have spent a while taxing my meagre brain on it > over the last few months, without much success ;-(
The thing is, in a lot of other contexts it can work easily because fcinfo->flinfo->fn_expr points the expression node for this function call, which means you can extract the relevent data out of that. This field is simply not filled in for type input/output functions. Something that has been discussed in the past is allowing non-strict type input/output functions to be evaluated at query execution time, rather than during parse time. This would give the type input/output functions the Expr node they need to extract this info. I have no idea how easy/hard this would be. Have a nice day, -- Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/ > From each according to his ability. To each according to his ability to > litigate.
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