dnl Copyright (C) 2012, 2014 The Meme Factory, Inc., http://www.meme.com/
dnl Copyright (C) 2007, 2008, Karl O. Pinc
dnl
dnl    This file is part of Gombe-MI.
dnl
dnl    Gombe-MI is free software; you can redistribute it and/or modify
dnl    it under the terms of the GNU General Public License as published by
dnl    the Free Software Foundation; either version 3 of the License, or
dnl    (at your option) any later version.
dnl
dnl    This program is distributed in the hope that it will be useful,
dnl    but WITHOUT ANY WARRANTY; without even the implied warranty of
dnl    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
dnl    GNU General Public License for more details.
dnl
dnl    You should have received a copy of the GNU General Public License
dnl    along with Gombe-MI.  If not, see <http://www.gnu.org/licenses/>.
dnl
dnl Deliver an error message on an attempt to change a computed value.
dnl Karl O. Pinc <kop@meme.com>
dnl
dnl
dnl m4 includes
include(`copyright.m4')
include(`constants.m4')
include(`macros.m4')
dnl

CREATE OR REPLACE FUNCTION
  _error_immutable(col TEXT)
  RETURNS INT
  LANGUAGE plpgsql
  gmi_function_set_search_path
  AS $$

  -- Raise error on an attempt to change an immutable column's value.
  --
  -- Copyright (C) 2014 The Meme Factory, Inc.  http://www.meme.com/
  -- GPL_notice(`  --', `2007', `Karl O. Pinc <kop@meme.com>')
  --
  -- Syntax:  _error_immutable(col TEXT)
  --
  -- Input:
  --   col   The immutable column.
  --
  -- Returns:
  --
  -- Side Effects:
  --   Raises an exception.
  --
  -- Remarks:
  --   Used when somebody tries to modify a view's computed column.


  DECLARE

  BEGIN
    RAISE EXCEPTION '%: Attempt to insert or update a computed or otherwise immutable column'
                  , col;
    RETURN 0;
  END;
$$;

grant_func_priv(`_error_immutable(TEXT)')