TADS - Direct and Indirect Objects

                     An article by Sue

One thing that I found very hard to get to grips with in TADS is
the use of direct and indirect objects. Well, it's a long time
since I did O Level English! Say you want the player to be able to
dig in a patch of earth with a fork and find an earthworm. Unless
you put specific code in the sections for both the earth and the
fork, 'dig earth with fork' won't work properly. It took me
ages to work out how to do it and now I just copy and adapt the
code for similar puzzles. Here is an example of the relevant
code from my forthcoming (assuming I don't reformat the hard drive
and lose the code - again!) game which will, I hope, help anyone
else having problems programming something similar.

earth: item
     sdesc = "sticky earth"
     adesc = {"some "; self.sdesc;}
     thedesc = {"the "; self.sdesc;}
     noun = 'earth' 'soil' 'patch'
     adjective = 'sticky'
     isListed = nil
     isdug = nil
     location = vegpatch
     ldesc = "It's a rich brown colour, well dug and containing
plenty of compost."
     verDoDigWith(actor,iobj)=
     {
     if (fork.location = Me.location)
         {
     "You'd better pick up the fork first!";
          }
     else if ((fork.isIn(Me)) and (earth.isdug=true))
          {
     "You dig around a bit more but the worms have got wise to
you and stay underground.";
           }
     }
;

 fork: item
     sdesc = "garden fork"
     adesc = {"a "; self.sdesc;}
     thedesc = {"the "; self.sdesc;}
     noun = 'fork'
     adjective = 'garden'
     location = vegpatch
     isstuckinground = true
     isListed = nil
     ldesc = "It is old and quite rusty."
     verIoDigWith(actor)={}
     ioDigWith(actor, dobj) =
     {
     if (earth.isdug = nil)
          {
     "You strike the fork into the earth. It goes in easily. You
move a few small clumps of earth to one side and disturb a group
of worms. Most wriggle off but one, which looks a bit stunned by
the experience, lies motionless on the surface.";
     worm.moveInto(vegpatch);
     earth.isdug:=true;
     incscore(3);
          }
     }
;













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