Re: [GENERAL] Geometric, getting x and y co-ordinates GOING MAD!!!!! - Mailing list pgsql-general

> I have no training in C so I've reached this far by trial and error.  I
> have however discovered that if write a function such as
>
> /* pants.c
>    weird of what! */
> #include "postgres.h"
> #include "utils/geo_decls.h"
> double
> pants(Point *pt)
> {
>     return 2.0;
> }
>
> and compile it as above and make it a function I get:
>
> brecard10=> select id,pos,pants(pos) from points;
> id|pos        |pants
> --+-----------+-----
>  1|(1,2)      |    1
>  2|(-1.3,4.77)| -1.3
>  3|(0,-3)     |    0
> (3 rows)
>
> HELP!
> WHAT'S GOING ON!!!
> Why can't I get to pt->y?
> Why does function pants behave just like get_x (and get_y)?

If you write your function as double, you can't declare it as float in sql. What you wanted is probably this:

#include "postgres.h"
#include "utils/geo_decls.h"

float32   x(Point *pt);
float32   y(Point *pt);

float32 x(Point *pt) {
        float32 result = (float32) palloc(sizeof(float32data));

        *result = (float)pt->x;
        return (result);
}

float32 y(Point *pt) {
        float32 result = (float32) palloc(sizeof(float32data));

        *result = (float)pt->y;
        return (result);
}

(note that float32 is a pointer type)

Then, in sql,

CREATE FUNCTION x(point)
RETURNS float4
AS '/home/postgres/src/point_adts/point_adts.so'   <- this is where the above x() and y() functions live
LANGUAGE 'c';

CREATE FUNCTION y(point)
RETURNS float4
AS '/home/postgres/src/point_adts/point_adts.so'
LANGUAGE 'c';


--Gene

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here's the complete working code:

begin 644 point_adts.tgz
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M_K%@]$\OOS*W(OLG257V6[M"J(`*<&8,3[^8X%&(;S$XB\":>;;E^XN*3RP'
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M;<W6EQ@EKRV)M(^%M2R*"`>.YR+$EM':V(@(;5Y;6X$D@HZFM@T5>FM%;+T5
MLBU2\M`4V3ZV@A8ZBF90<;><KP=*$H'2'R@5T"ORO]7_7L!:P?<EEN/]UMA+
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M;M3J1,C*YT$%%Y'1&9Q/.N<Z%.WB"3L?'L59O&V<<>?4T"$$(5SUDLBD_L#4
M1V/H#\9#IGSK&!/=%(J"7%;%(M.?D"M*67M.5R6U_$GZN#1!R-0-O3M.=E$L
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MVSS*1MD%ZM/J%)-K!]O^4D3+5JVS/+$ZOTR*!DIATF'9^.+!^$;8-H=?*,U_
M*K/@<S^&-@CK$1%"=B$16Z#>3TS<=-BQ8DM,_*8.2H^^%,.X\OG^9*-'.)Y'
M`0@K,_;E[VQ.BT/.:?'\G/YU,7`X'`Z'P^%P.!P.A\/A<#@<#H?#X7#>/7\!
(A%`/L@`H````
`
end