Reverse Engineering

Whereigo cartridges are based on the Lua scripting language. Using facilities built into Lua, you can find out information about the properties and methods of the various objects which are part of the programming model.

Getting Started

To begin, create and publish a dummy cartridge to your local machine. Something created with the wizard will do nicely. Open the emulator and load your cartridge into it. Click Play. Now switch to the Lua Debug tab.

The Basic Script

Veeerrrrry carefully, type the following in the command box. Remember that Lua is case-sensitive. Better yet, copy and paste from here. The example examines the Player object. You can change the first line to examine any object instance which is accessible.

local o = Player;

print(o);

print(getmetatable(o));

for k,v in pairs(getmetatable(o)) do print(k,v) end;

print(getmetatable(o)._self);

for k,v in pairs(getmetatable(o)._self) do print(k,v) end;

Click the Execute Lua Command... button. Your results will appear in the result box. Counterintuitively, they appear in reverse order with the output of your last statement at the top of the result list. The result box lacks a vertical scroll bar. To see all of your results, you may need to click in the result box. Then use standard Windows text navigation keys (such as up- and down-arrow, page-up and page-down, etc.) to navigate.

What You Get

The above commands should show something like this:

GetVisibleObjects function: 036A5890

GetVisibleInventory function: 036A5918

PositionAccuracy Distance(1, 'm')

CurrentBearing false

Commands table: 0366B1F0

Name Builder

Icon false

GetContainer function: 0364A7E8

Cartridge a ZCartridge instance

ObjIndex -21555

Gender It

CommandsArray table: 0366B218

SetObjectLocation function: 0364A900

GetActiveVisibleZones function: 03685130

IsObjectVisible function: 036A58B0

RefreshLocation function: 03668400

Container false

CurrentDistance false

serialize function: 03660988

ProcessLocation function: 036683E0

InsideOfZones table: 03685108

Description

InsideOf function: 036A5938

Inventory table: 036472D8

OnEnterZone function: 0364A850

OnExitZone function: 0364A898

Id -1

LastLocationUpdate 1203287121

Type PC

OnSetInventory function: 0364A830

GetActiveVisibleTasks function: 036A5818

GetActiveTimers function: 036A58D0

CompletionCode builder

ObjectLocation ZonePoint(38.636607, -90.574608, Distance(0, 'm'))

Media false

Visible false

table: 036A4A98

newindex function: 0368AD70

tostring function: 0366D9A0

_self table: 036A4A98

index function: 0368AD90

table: 03647200

a ZCharacter instance

What It Means

Reading from the bottom up:

print(o) yields "a ZCharacter instance", which tells us the class of the the object Player. (Every instance exposes some information about itself when you simply print it. The amount and usefullness of the information varies according to the definition of the class.)

print(getmetatable(o)) yields "table: 03647200". This just tells us that the Player object has a metatable which describes itself.

for k,v in pairs(getmetatable(o))... yields the lines beginning with index and ending with __newindex. This is not useful information. I only left this step in so you can see where we get the reference to _self.

print(getmetatable(o)._self) yields "table: 036A4A98". Just tells us that ._self is also a table.

for k,v in pairs(getmetatable(o)._self)... yields all the remaining lines, which are the visible properties and methods on the Player object.

Of course, this doesn't really give us enough information to call methods. And I'm sure it exposes a number of things which we should not play with. On the other hand, several of the properties on the Player object (such as ObjectLocation and PositionAccuracy) have been discussed in the forums. So at least you have things about which you can ask specific questions.