[postgis-devel] Is there a reason those GArray functions aren't documented?
robe.dnd at cityofboston.gov
Tue Jul 1 03:48:46 PDT 2008
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
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
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
RETURNS geometry AS
LANGUAGE 'sql' IMMUTABLE;
COMMENT ON FUNCTION upgis_makepolygonfrompoints(geometry) IS 'Takes an
array of points and returns a polygon formed from those points.
ST_MakePoint(2,0), ST_MakePoint(1,0), ST_MakePoint(1,1)]) ';
Which allows me to do something perverse like this
ST_MakePoint(2,1), ST_MakePoint(2,0), ST_MakePoint(1,0),
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