anchor.diff:        makeFlags="PERL=${perl}/bin/perl datadir=$out/share pkglibdir=$out/lib bindir=$out/bin"
       '';
   
  -    pg_db_postgis_enable = ./pg_db_postgis_enable.sh;
  -
  -    scriptNames = [ "pg_db_postgis_enable" ]; # helper scripts
  -
  -    # prepare fixed parameters for script and create pg_db_postgis_enable script.
  -    # The script just loads postgis features into a list of given databases
  -    postgisEnableScript = ''
  -      s=$out/bin/pg_db_postgis_enable
  -
  -      sql_comments=$out/share/postgis-${version}/comments.sql
  -      mkdir -p $(dirname $sql_comments)
  -      cp $(find -iname ${fix.fixed.sql_comments}) $sql_comments
  -
  -      for script in $scriptNames; do
  -        tg=$out/bin/$script
  -        substituteAll ''${!script} $tg
  -        chmod +x $tg
  -      done
  -    '';
  -
  -    # create a script enabling postgis features
  -    # also create aliases for all commands adding version information
  +    # create aliases for all commands adding version information
       postInstall = ''
   
         sql_srcs=$(for sql in ${builtins.toString fix.fixed.sql_srcs}; do echo -n "$(find $out -iname "$sql") "; done )
   
  -      eval "$postgisEnableScript"
  -      eval "$postgisFixLibScript"
  -
  -      for prog in $out/bin/*; do
  +      for prog in $out/bin/*; do # */
           ln -s $prog $prog-${version}
         done
   
  
positive.code: args@{fetchurl, composableDerivation, stdenv, perl, libxml2, postgresql, geos, proj, flex, ...}:
  
    /*
  
  
negative.code:   ==================
  
      services.posgresql.extraPlugins = [ pkgs.postgis.v_1_5_1 ];
  
      services.postgresql.extraPlugins = [ (pkgs.postgis.override { postgresql = pkgs.postgresql94; }).v_2_1_4 ];  # BM - 2015/01/01
  
      or if you want to install 1.5.x and 1.3.x at the same time (which works
      because the .sql and .so files have different names):
  