Re: make tuplestore helper function

On Mon, Feb 28, 2022 at 04:49:41PM +0900, Michael Paquier wrote:
> In order to keep things pluggable at will, MakeFuncResultTuplestore()
> has been changed to access a set of bits32 flags, able to control the
> two options above.  With this facility in place, I have been able to
> cut much more code than the initial patch, roughly twice as of:
>  24 files changed, 157 insertions(+), 893 deletions(-)

So, I have been thinking about this patch once again, and after
pondering more on it, MakeFuncResultTuplestore() is actually a wrong
name now that it does much more than just creating a tuplestore, by
assigning the TupleDesc and the TupleStore into the function's
ReturnSetInfo.

This is actually setting up a function in the context of a single call
where we fill the tuplestore with all its values, so instead I have
settled down to name that SetSingleFuncCall(), to make a parallel with
the existing MultiFuncCall*().  funcapi.c is the right place for
that, and I have added more documentation in the fmgr's README as well
as funcapi.h.
--
Michael