before

before and its partner object property, after, are two of the more complicated object properties. The information contained therein determines what code should be run before normal actions (with their standard responses) are allowed (and whether normal code execution is allowed at all).

Defined by the compiler

before is one of six properties defined by the compiler (and not by the standard library). If we could see its definition, it’d look something like this:

property before $additive $complex

Let’s take a look at those two extra parameters:

• $additive tells the compiler that a before routine “defined in an inherited class or object is not overwritten by a new property routine in the new object.” What I (Roody Yogurt) believe this means is that this is allowed:

class rock "rock"
{
    noun "rock"
    before {
           object DoListen
              {
              "It sounds like a rock."
              }
           }
}

rock big_rock "big rock"
{
    adjective "big"
    before  {
            object DoGet
               {
               "It is much too big."
               }
            }
}

The big_rock object will inherit the rock object’s DoListen response. As far as I (Roody Yogurt) can understand, this is the extent of $additive’s functionality.

• $complex just tells the compiler to expect the routine to be in the before/after layout, which would not work as a standard routine.

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Usage

The parts:

• usage Possible entries: actor, object, xobject, location, parent(player) (the last one only called by DoGo- When the routine BeforeRoutines calls things like player.before, location.before, and object.before, the before property of the object set to the applicable global variable is called. If the usage is true for the current object, it goes on to check the verb routine and so forth.
• verbroutine- This is obviously the verb routines we are trying to catch, either because we want to prevent the action or just change its outcome. If there is no verb routine, the block code will be applied to all verbs. In some cases- like when the usage parameter is the location global variable- this will also apply to xverbs. To get around this, use AnyVerb.
• the block code- This is where you put the text you want to print instead or the code that just alters some global value or something before letting routines go on as normal. Unless the block code explicitly returns false, the action-processing will stop right there. If you want the action to go on, return false!

before order

The order of before properties is explained on things like the Game Loop page, but you can also get it straight from the horse’s mouth by taking a look at hugolib.h’s BeforeRoutines routine.