[postgis-tickets] [PostGIS] #2965: ST_Distance, use_spheroid default

[PostGIS]

#2965: ST_Distance, use_spheroid default
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  Reporter:  gitai     |       Owner:  pramsey                  
      Type:  defect    |      Status:  closed                   
  Priority:  critical  |   Milestone:  PostGIS 2.1.5            
 Component:  postgis   |     Version:  2.1.x                    
Resolution:  wontfix   |    Keywords:  ST_Distance, use_spheroid
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Comment(by robe):

 gitai -- I don't think there is a way to satisfy this request short of
 what Pramsey is saying of removing the autocast in geometry::geography
 which many have complained about so would be a good enhancement in my
 book.

 Both geometry and geography have ST_Distance functions (that take no
 additional args but the spatial objects) and geography is the only one to
 take the additional use_spheroid option which is how you managed to fall
 into the lucky trap.

 So when you use the 2 argument one since you have 2 geometries it goes
 into the best fitting function (that ST_Distance that takes geometries).
 When you pass it the additional arg, only the geography version has the
 extra arg -- and geometry says -- hey I can pretend to be a geography to
 get myself in this door. By the time it gets into the function door, it
 already has been cast to a geography so there is no way we can provide a
 hint to say "hey dude you just morphed yourself into a geography".


 So the fact you happened to waltz into the right geography function when
 passing your geometries in is nothing we can  protect you from short of
 removing the autocast or renaming our functions to have Geom / Geog in
 name. Such a renaming would annoy a lot of people.  However I do think
 many people (I included) would like the proposed get rid of the autocast.
 The autocast bytes you in very  subtle ways like when when doing &&
 between a geometry and geograpy

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/2965#comment:17>
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