CheckReach

Definition

calling form	description
CheckReach(object)	Checks to see if the specified object is within reach of the player object. Returns true if accessible; returns false and prints an appropriate message if not accessible.

From this simple description from the manual, one might imagine that CheckReach can be used whenever you want to check whether a player can take or manipulate an object. This is not true (FindObject is much better suited for that task). CheckReach is a routine used specifically for situations where some objects are out of reach (like when the PC is in a chair or vehicle). In fact, to work properly, it requires you to set a reach property for the object that the player is in.

Stuck to the couch

Let’s jump straight into an example:

room STARTLOCATION "Living Room"
{
    long_desc
        "Woo, it's your living room."
}

object tv "television"
{
    in STARTLOCATION
    article "the"
    noun "tv","television"
    long_desc  {
            if self is switchedon
            "The tv is on."
            else
            "The tv is off."
           }
    before
        {
        object DoSwitchOn
            {
            if parent(remote) = player
                {
                "You turn on the television with the remote."
                tv is switchedon
                return true
                }
            else
                return false
            }
        }
    is switchable, static
}

object couch "couch"
{
    article "the"
    nearby tv
    noun "couch"
    reach table remote
    is enterable, platform, static
}

object table "coffee table"
{
    article "the"
    nearby tv
    adjective "coffee"
    noun "table"
    is static, platform
}

object remote "remote control"
{
    article "the"
    adjective "remote"
    noun "remote","control"
    in table
}

A transcript of a game using this sparse code would look like this:

Living Room, on the couch
Woo, it’s your living room.
The television and the coffee table are here. Sitting on the coffee table is the remote control.

>turn on tv
You can’t reach the television from the couch.

>get remote
Taken.

>turn on tv
You turn on the television with the remote.

>x tv
The tv is on.

CheckReach in verb routines

In the couch object above, you’ll notice how the reach property is followed by a list the objects you can interact with. Everything else, you can only examine or look into. This is because almost every verb in verblib.h runs CheckReach. For example, take a look at DoMove:

routine DoMove
{
    if not CheckReach(object):  return false

    VMessage(&DoMove)                ! "You can't move that."
    return true
}

When you add new verbs to your games, remember that if it is a verb affected by reach, you’ll want to add a similar CheckReach line.

Other things to keep in mind:

If you want the player to not reach anything, try giving the enterable object a reach property of 1.

CheckReach will not work properly if object.before properties get in the way. If you have an object with a special failure message for DoGet, you’ll have to add a line like if player in <reach affecting object>:return false or if not CheckReach(object): return true (we return true so CheckReach is called only once) to your object.before.object DoGet code.

CheckReach and components

The current CheckReach requires that an object within reach also has all of its components explicitly listed in the reach property. If you want a version that automatically checks for components, look at “replace CheckReach”.