[postgis-devel] Is there a reason those GArray functions aren't documented?

[Obe, Regina]

I was assuming it is because we consider them internal like functions
since they are used to form the aggregate functions and may be something
that changes in the future.  

I finally found a use for them somewhat directly and felt a little dirty
using them.

Case in point.  Someone asked me how to formulate a polygon if he has a
known finite set of points he pulled out of a hat (well a hat that forms
points forming a closed ring - not coming from an aggregate rollup)

After looking thru the docs and the closest thing I could come up with
using documented
functions was

ST_MakePolygon(ST_LineFromMultiPoint(multipoint))

which would require me to get my points into a multipoint (using yet
another undocumented GArray function or using a messy union all).


I then found all these undocumented garray functions used to form the
aggregates which allowed me to write a function using ST_MakeLineGArray.

CREATE OR REPLACE FUNCTION upgis_makepolygonfrompoints(points
geometry[])
  RETURNS geometry AS
$BODY$
	SELECT ST_MakePolygon(ST_MakeLine_GArray($1))

$BODY$
  LANGUAGE 'sql' IMMUTABLE;

COMMENT ON FUNCTION upgis_makepolygonfrompoints(geometry[]) IS 'Takes an
array of points and returns a polygon formed from those points.  
	USAGE: SELECT
upgis_makepolygonfrompoints(ARRAY[ST_MakePoint(1,1), ST_MakePoint(2,1),
ST_MakePoint(2,0), ST_MakePoint(1,0), ST_MakePoint(1,1)]) ';


Which allows me to do something perverse like this

SELECT upgis_makepolygonfrompoints(ARRAY[ST_MakePoint(1,1),
ST_MakePoint(2,1), ST_MakePoint(2,0), ST_MakePoint(1,0),
ST_MakePoint(1,1)]);


Thanks,
Regina

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