Coding

To Run, Host, Compile, And Develop on SS13 Go To The Goonstation Development Guide

Be sure to follow it exactly!

Discord is the place to talk to fellow players, admins, and devs in realtime. There's plenty of friendly people there, capable of answering most of your questions. Join at This Invite Link If you have problems with the above guide, visit ##imcoder

All of these links and more can be found at https://github.com/goonstation/goonstation

You can also take a look at DM by Example guide here: [1]

Introduction to DM as a language

DM is a high-level programming language, meaning, effectively, that its use does not require much understanding of computer hardware. Its purpose is the creation of games, and so tricky things like memory management are smoothed over for the coder's convenience. This is done by way of a process virtual machine: .DM source code is compiled not into machine language, but into a binary format designed specifically for BYOND. For a Dream Maker Binary (.DMB) to run it must be hosted by Dream Daemon, one of BYOND's four executables (Dream Seeker, the program used to play BYOND games, can also host them, but it is not recommended for Space Station 13).

BYOND, being patterned on C++, is an object-orient programming language. Abstract classes are defined in the code, which serve as templates for objects manipulated by functions. Suppose, for example, you are making a game with bears. You define all the variables and functions associated with them: What they're called, how they move, etc. This is the bear class. Whenever a bear comes into existence within the game, an object of this class is instantiated. Though its variables are derived from its class, changes made to them are made only to that specific bear; neither other bears nor the template itself are affected.

The concept of inheritance is central to object-oriented programming. One class can be derived from another, such that they share everything defined in the parent class. For instance, you might wish your game to feature a special type of bear. The path for a bear is <syntaxhighlight lang='cpp' line='none' enclose='none'>/mob/bear</syntaxhighlight> (bear is itself a child of mob, a built-in class which will be discussed later). Therefore, you make a subclass <syntaxhighlight lang='cpp' line='none' enclose='none'>/mob/bear/fuzzy_wuzzy</syntaxhighlight>. Any changes to /bear affect /bear/fuzzy_wuzzy, but not vice-versa. You can even define subtypes of inherited functions, a practice known as overloading. Suppose /bear has a function called sylvan_defecation, rendered in DM as <syntaxhighlight lang='cpp' line='none' enclose='none'>/mob/bear/proc/sylvan_defecation()</syntaxhighlight>. However, you want bears of the /fuzzy_wuzzy variety to behave differently when answering nature's call, and so you overload that function by defining <syntaxhighlight lang='cpp' line='none' enclose='none'>/mob/bear/fuzzy_wuzzy/sylvan_defecation()</syntaxhighlight> (note the absence of /proc/). Whenever a function calls sylvan_defecation() on a bear that belongs to the /fuzzy_wuzzy/ subclass, it will execute its special version of that function.

DM, as we discussed above, is executed by way of a process virtual machine. This means that, though it shares much of C++'s syntax and logic, it is ultimately a lot simpler. As such, it is not overly concerned with rigid type-management. A variable might represent a number one moment and a string the next. Such a transformation can still cause all manner of errors, if the coder does not account for it, but it won't necessarily cause the game to crash. In most cases Dream Daemon will simply shrug, inform you of your blunder, and carry on to the best of its abilities. This sort of extreme looseness is of dubious efficacy, but it means that you won't need to fret about the number of bytes allocated to a given value, whether a number can be negative, and other such distracting things.

ATOMs and Datums

As mentioned above, BYOND has certain built in classes. The first of these is /datum. This is simply the ancestral class, from which all others are derived; note that a class defined with no explicit parent is considered a child of /datum. From /datum comes /atom, the fundamental class for things in the game world. Simply put, if a thing is on the map, it derives from /atom. This brings us to the four elemental classes: /turf, /area, /mob, and /obj. Note that /turf and /area are derived directly from atom, whereas /mob and /obj are derived from /atom/movable. Only objects derived from the elemental classes can exist on the map; this contrivance means there is no point in defining direct descendants of /atom and /atom/movable.

The /obj class is something of a catchall for movable objects. You might derive from it classes for machines, items, or even creatures. Anything player-controllable, however, must belong to /mob, intended exclusively for creatures. Both objs and mobs within the map are contained by objects of the class /turf/. A turf is simply a tile on the map. Being as it is a point on a grid, a turf cannot move. Turfs, in turn, are contained by objects of the class /area. Areas are meant for use as zones or rooms. In the same way that multiple items can be contained within a single map tile, multiple map tiles can be contained within a single area. You might, for example, wish for a certain sound to play when a player is in a given room, or for certain creatures to be barred from certain places, or goodness knows what else. The possibilities are myriad.

It should be noted that there exist built-in classes not mentioned here, such as /client or /image, but they are not relevant at present.

In summary, the line of descent is as follows:

• /datum
• /datum/atom
• /datum/atom/area
• /datum/atom/turf
• /datum/atom/movable
• /datum/atom/movable/obj
• /datum/atom/movable/mob

Licenses and Stuff

Historical Structure

Goonstation formerly stood at a weird intersection of open- and closed-source. Most of the code is closed-source, kept away from the public; however, some coders may share some code with you, particularly if you want to make a patch. In addition, there have been two public releases of the source code: one from March 2016 and one from 2020, which contains the source as it was on January 1st, 2020, with certain secrets and other things plucked out. Pretty much all the patches made at the time used code from these repositories. So, if closed source is a walled garden, Goonstation was a walled garden that occasionally let people in to study the gardening techniques and landscape patterns used, and sometimes, it released books and treatises explaining how the garden is constructed.

Current Structure

As of April 1st, 2020, the goonstation administration made the decision to make the code open-source; for the interested, a statement from the admins exists at this link. The new open source is found here. Some elements are still kept secret, particularly content designed to be secret so it can't just be instantly looked up and figured out; but the vast majority of the code is now maintained there.

License

Goonstation is specifically licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License, or just CC BY-NC-SA 3.0 US. It's best explained on its dedicated page on the Creative Commons website, but it essentially means people like you can contribute code to Goonstation, using code from the public releases, open source release, and/or snippets of code shared by people on the Goonstation coder team, and the only lawyers you'll have to worry about are ones in-game.