# fueled.t | documentation

    #charset "us-ascii"

    #include <tads.h>
    #include "advlite.h"

    /*
     *   fueled.t
     *
     *   The FUELED LIGHT SOURCE extension is intended for use with the adv3Lite
     *   library. It provides the FueledLightSource mix-in class which can be used
     *   to implement a light source with limited life.
     *
     *   VERSION 1
     *.  21-Jul-13
     *
     *   Usage: include this extension after the adv3Lite library but before your
     *   own game-specific files. Make sure that events.t is also included in your
     *   build.
     */

    fueledID: ModuleID
        name = 'Fueled Light Source'
        byline = 'by Eric Eve'
        htmlByline = 'by Eric Eve'
        version = '1'
    ;

    /*
     *  A FueledLightSource is a light source that stars out with a set amount
     *  of fuel, which is then consumed at one unit per turn. Once the fuel
     *  is exhausted the FueledLightSource goes out and can't be re-lit until
     *  it has been refueled. [PART OF FUELED EXTENSION]
     */
    class FueledLightSource: object
        /*
         *   The source of our fuel. By default this is self, but it could be an
         *   external source such as a battery
         */
        fuelSource = self

        /*
         *   Our remaining fuel level. The default is a modest level but this can be
         *   overridden on particular instances.
         */
        fuelLevel = 20

        /*   A note of our fuelDaemon's ID, if one is running. */
        fuelDaemonID = nil

        /*
         *   Start our fuelDaemon running in a SenseDaemon (so no messages are
         *   displayed if the player character can't see us).
         */
        startFuelDaemon()
        {
            if(fuelDaemonID == nil)
                fuelDaemonID = new SenseDaemon(self, &fuelDaemon, 1);
        }

        /*
         *   Stop the fuelDaemon; first check that we actually have one and then
         *   disable it.
         */
        stopFuelDaemon()
        {
            if(fuelDaemonID != nil)
            {
                fuelDaemonID.removeEvent();
                fuelDaemonID = nil;
            }
        }

        /*  The fuelDaemon is executed every turn this object is lit */
        fuelDaemon()
        {
            /* Reduce the fuel level of our fuel source */
            fuelSource.fuelLevel--;

            /* Optionally show a warning message if the fuel is running low. */
            showWarning();

            /*
             *   If we're out of fuel, stop the fuelDaemon, make us no longer it,
             *   and display a message explaining that we've just gone out.
             */
            if(fuelSource.fuelLevel < 1)
            {
                stopFuelDaemon();
                isLit = nil;
                sayBurnedOut(true);
            }
        }

        /*
         *   The showWarning() message can be used to display a message warning when
         *   this light source is about to go out. One way to do this would be via a
         *   switch statement that looks at the value of fuelSource.fuelLevel and
         *   displays warning messages when that reaches low values. There's no need
         *   for this message to display anything when the fuelLevel is zero,
         *   however, since that is handled by sayBurnedOut().
         */
        showWarning() { }

        /*  The message to display when we run out of fuel */
        sayBurnedOut(fromDaemon?)
        {
            /* Create a convenient message parameter substitution */
            local obj = self;
            gMessageParams(obj);

            /* Say that we've gone out. */
            say(burnedOutMsg);

            /*
             *   If our going out has left the player character in darkness, say so.
             */
            if(!gPlayerChar.location.litWithin && fromDaemon)
                say(plungedIntoDarknessMsg);
            ". ";
        }

        burnedOutMsg = BMsg(say burned out, '{The subj obj} {goes} out')
        plungedIntoDarknessMsg = BMsg(plunged into darkness, ', plunging {1} into
            darkness', gPlayerChar.theName)

        /* Modifications to the makeLit() method for FueledLightSource [FUELED EXTENSION] */
        makeLit(stat)
        {
            /*
             *   If someone's trying to make us lit and we don't have a fuel source
             *   or our fuel source is out of fuel, say that we won't light and stop
             *   there.
             */
            if(stat && (fuelSource == nil || fuelSource.fuelLevel < 1))
            {
                say(wontLightMsg);
                return;
            }

            /*
             *   If we're being lit, start our fuelDaemon, otherwise, stop our
             *   fuelDaemon.
             */
            if(stat)
                startFuelDaemon();
            else
                stopFuelDaemon();

            /*  Carry out the inherited handling. */
            inherited(stat);
        }

        /*
         *   The message to display when we can't be lit because we have no fuel.
         *   Most instances will probably want to override this to something more
         *   specific.
         */
        wontLightMsg = BMsg(wont light, '\^{1} {dummy} {won\'t} light. ', theName)

        /*
         *   If we have an external fuel source then removing or disabling it will
         *   have certain consequences, so code that, for example, you can call this
         *   method if a battery is removed from a flashlight.
         */
        removeFuelSource()
        {
            if(isLit)
            {
                isLit = nil;
                stopFuelDaemon();
                sayBurnedOut();
            }
            fuelSource = nil;
        }

    ;

Adv3Lite Library Reference Manual
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