! >BL  The class Block provides for stackable building blocks.
!
!   Note that with the "describe" routine missing, the game would still
!   correctly describe stacks of blocks: just a little less elegantly.
! ----------------------------------------------------------------------------

Class  Block
  with description "Just a child's building block, four inches on a side.",

       !   The parse_name routine below ensures that "take blocks"
       !   works correctly:

       parse_name
       [ i j;
         for (::)
         {   j=NextWord();
             if (j=='block' or 'cube' or 'building' or (self.name)) i++;
             else
             {   if (j=='blocks' or 'cubes')
                 {   parser_action=##PluralFound; i++; }
                 else return i;
             }
         }
       ],

       describe
       [ c d e;
           d = child(self);
           while (d~=0 && d ofclass Block)
           {   c++; e=d; d=child(d); }
           if (c==0) rfalse;
           print "^There is a pile of building blocks here, ";
           while (c>=0)
           {   print (address) e.name;  ! Sneaky: print the "name" out
               if (c>0) print " on ";   ! using its dictionary address
               c--; e=parent(e);
           }
           ".";
       ],
       before
       [ c;
         PutOn:
           if (second ofclass Block)
           {   if (child(second)~=0 && child(second) ofclass Block)
                   "There's no room on the top of one cube for two more, side 
                    by side.";
           }
           else
               print "(They're really intended 
                      to be piled on top of each other.)^";
           c=second; while (c ofclass Block) c=parent(c);
           if (c~=location or mantelpiece) "Too unsteady a base.";
       ],
       after
       [ c stack;
         PutOn:
           stack=noun;
           while (parent(stack) ofclass Block) { stack=parent(stack); c++; }
           if (c<2)
           {   if (Chris has general) rtrue;
               rfalse;
           }
           if (c==2) "The pile of three cubes is unsteady, but viable.";
           if (Chris has general)
           {   Achieved(3);
               "^Expertly he keeps the pile of four cubes stable.";
           }
           stack=noun;
           while (parent(stack) ofclass Block)
           {   c=stack; stack=parent(stack); move c to location; }
           "The pile of four cubes wobbles, wobbles, steadies... and suddenly 
            collapses!";
         Take:
           stack=child(noun); if (stack==0) rfalse;
           while (stack~=0)
           { c=stack; stack=child(stack); move c to location; }
           "Your pile of cubes is collapsed as a result.";
       ],
  has  supporter;

Block -> "green cube"
  with name "green";
Block -> "red cube"
  with name "red";
Block -> "yellow cube"
  with name "yellow";
Block -> "blue cube"
  with name "blue";

! ----------------------------------------------------------------------------