DoGo

DoGo is the verb routine used almost every time the player goes anywhere (surprise, surprise). As authors, we often want to interject messages or otherwise modify the normal behavior, so a good understanding of DoGo is beneficial. In the section below, the DoGo routine is presented. Support for games that don’t include objlib.h has been omitted in an effort to make it slightly more readable (it’s a multifaceted routine).

The DoGo “walkthrough”

Reading it from top to bottom, we can see it do the following things:

1. If the player is in another object (a vehicle or, say, on a couch):
   1. directions other than “up” and “out” will give a “You’ll have to get out.” message. Keep this in mind when you have objects that a player should be able to leave by typing “down” (like a horse).
   2. The player’s parent object is checked for a before routine. Uunfortunately, this code is only reached if the direction is “up” or “out” and if there is a before routine, a turn will pass (which is suboptimal for certain messages).
2. If the obstacle variable has been set to an object, it prints the response “
3. If the direction object is valid, jump ahead to the “valid direction” section.
4. If there isn’t an object (or if there is an object but it isn’t a direction object):
   1. If no object, say “Which way?”
   2. If the object doesn’t have a door_to property, check if it’s enterable. If so, enter the object.
   3. Set the moveto local variable to the object’s door_to property.
      1. If moveto = 0 (there was no door_to property), say “You can’t enter that.”
      2. If moveto = 1, the door_to property was just a printed string. DoGo will just leave it at that.
      3. (at the bottom of the routine) Perform MovePlayer(moveto)
5. If the object is a valid direction (or if the above door_to code had returned a direction object instead of a room object):
   1. If the player is in an object:
      1. If the player is on a platform, any direction other than “up” will give a “you’ll have to go out” message (and “up” will successfully exit).
      2. If the player is in a container, any direction other than “out” will give a “you’ll have to go out” message (and “out” will successfully exit).
   2. Reset moveto to whatever the current direction leads to.
      1. If it returns an object with a door_to property or a door, change moveto to the door_to property.
   3. If moveto is false (there’s no exit in that direction):
      1. Check if the current location has a cant_go property and print it. If not, do the default “You can’t go that way.” message.
      2. If moveto = 1, the direction only printed something.
   4. Again, if the player is in something, there is a “You’ll have to get up.” message
   5. Lastly- and we should only get to this code if moveto is set to a viable room location- MovePlayer the player to that location.

The code

routine DoGo
{
    local moveto

    if player not in location               ! sitting on or in an obj.
    {
        if object ~= u_obj and object ~= out_obj
            {
            VMessage(&DoGo, 3)      ! "You'll have to get up..."
            return false
            }
        if parent(player).before    ! i.e., a vehicle, etc.
            return true
    }
    elseif obstacle
    {
        VMessage(&DoGo, 1)      ! "X stops you from going..."
        return true
    }

    ! See if the object is one of the current direction set
    if object.type = direction and object in direction
        {
        moveto = object
        jump FoundDirection
        }

    if not moveto
        {
        if not object
            {
            ! ParseError(6)  ! doesn't make any sense
            VMessage(&DoGo, 4)  ! "Which way...?"
            return
            }
        if not &object.door_to
            {
            if not object.door_to and object is enterable
                return Perform(&DoEnter, object)
            }
        moveto = object.door_to
        if not moveto
            {
            VMessage(&DoEnter, 2)  ! "You can't enter..."
            return
            }
        if moveto = 1
            return true
        }

:FoundDirection
    if moveto.type = direction and moveto in direction
        {
        if player not in location and object = out_obj
            {
            if parent(player) is platform
                {
                VMessage(&DoGo, 3)
                return false
                }
            else
                return Perform(&DoExit)
            }
        elseif player not in location and object = u_obj
            {
            if parent(player) is container
                {
                VMessage(&DoGo, 3)
                return false
                }
            else
                return Perform(&DoExit, parent(player))
            }

        moveto = location.(moveto.dir_to)
        if &moveto.door_to or moveto.type = door
            moveto = moveto.door_to
        }

    if moveto = false
        {
        if not location.cant_go
            VMessage(&DoGo, 2)      ! "You can't go that way."
        return false
        }

    elseif moveto = true                    ! already printed message
        return true                     ! (moveto is never 1)

    elseif player not in location           ! sitting on or in an obj.
        {
        VMessage(&DoGo, 3)              ! "You'll have to get up..."
        }
    else
        {
        MovePlayer(moveto)
        return true
        }
}