narya/src/as/com/threerings/util/Controller.as

package com.threerings.util {

import flash.events.IEventDispatcher;

import com.threerings.mx.events.CommandEvent;

public class Controller
{
    /**
     * Set the panel being controlled.
     */
    protected function setControlledPanel (panel :IEventDispatcher) :void
    {
        if (_controlledPanel != null) {
            _controlledPanel.removeEventListener(
                CommandEvent.TYPE, handleCommandEvent);
        }
        _controlledPanel = panel;
        if (_controlledPanel != null) {
            _controlledPanel.addEventListener(
                CommandEvent.TYPE, handleCommandEvent);
        }
    }

    /**
     * Post an action so that it can be handled by this controller or
     * another controller above it in the display list.
     */
    public final function postAction (cmd :String, arg :Object = null) :void
    {
        CommandEvent.dispatch(_controlledPanel, cmd, arg);
    }

    /**
     * Handle an action that was generated by our panel or some child.
     *
     * @return true if the specified action was handled, false otherwise.
     *
     * When creating your own controller, override this function and return
     * true for any command handled, and call super for any unknown commands.
     */
    public function handleAction (cmd :String, arg :Object) :Boolean
    {
        // fall back to a method named the cmd
        var fn :Function = null;
        try {
            fn = (this[cmd] as Function);
        } catch (e :Error) {
            // suppress
            //Log.testing("Caught error finding '" + cmd + "()' [" + this + "]");
        }
        if (fn == null) {
            // try the old style with "handle" prepended
            try {
                fn = (this["handle" + cmd] as Function);
            } catch (e :Error) {
                // suppress
                //Log.testing("Caught error finding 'handle" + cmd + "()' [" +
                //    this + "]");
            }
        }
        if (fn != null) {
            try {
                try {
                    // try calling it with the arg
                    fn(arg);
                } catch (ae :ArgumentError) {
                    if (arg == null) {
                        // try calling it without the arg
                        fn();
                    } else {
                        throw ae;
                    }
                }

            } catch (e :Error) {
                var log :Log = Log.getLog(this);
                log.warning("Error handling controller " +
                    "command [error=" + e + ", cmd=" + cmd +
                    ", arg=" + arg + "].");
                log.logStackTrace(e);
            }
            // we "handled" the event, even if it threw an error
            return true;
        }

        return false; // not handled
    }

    /**
     * Private function to handle the controller event and call
     * handleAction.
     */
    private function handleCommandEvent (event :CommandEvent) :void
    {
        if (handleAction(event.command, event.arg)) {
            // if we handle the event, stop it from moving outward to another
            // controller
            event.markAsHandled();
        }
    }

    /** The panel currently being controlled. */
    protected var _controlledPanel :IEventDispatcher; 
}
}