Re: Make COPY format extendable: Extract COPY TO format implementations

Hi,

In <CAD21AoC_dhfS97DKwTL+2nvgBOYrmN9XVYrE8w2SuDgghb-yzg(at)mail(dot)gmail(dot)com>
"Re: Make COPY format extendable: Extract COPY TO format implementations" on Wed, 10 Jan 2024 15:33:22 +0900,
Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:

>> We can use the satic const struct approach by choosing one
>> of the followings:
>>
>> ...
>>
>> 4. ... other idea?
>
> It's a just idea but the fourth idea is to provide a convenient macro
> to make it easy to construct the CopyFormatRoutine. For example,
>
> #define COPYTO_ROUTINE(...) (Node *) &(CopyToFormatRoutine) {__VA_ARGS__}
>
> static const CopyFormatRoutine testfmt_copyto_handler = {
> .type = T_CopyFormatRoutine,
> .is_from = true,
> .routine = COPYTO_ROUTINE (
> .start_fn = testfmt_copyto_start,
> .onerow_fn = testfmt_copyto_onerow,
> .end_fn = testfmt_copyto_end
> )
> };
>
> Datum
> copy_testfmt_handler(PG_FUNCTION_ARGS)
> {
> PG_RETURN_POINTER(& testfmt_copyto_handler);
> }

Interesting. But I feel that it introduces another (a bit)
tricky mechanism...

BTW, we also need to set .type:

.routine = COPYTO_ROUTINE (
.type = T_CopyToFormatRoutine,
.start_fn = testfmt_copyto_start,
.onerow_fn = testfmt_copyto_onerow,
.end_fn = testfmt_copyto_end
)

Thanks,
--
kou