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CONTRIBUTING

  1. Reporting Issues
  2. Introduction
  3. Getting Started
  4. Meet the Team
    1. Headcoder
    2. Maintainers
    3. Issue Managers
  5. Specifications
  6. Pull Request Process
  7. Porting features/sprites/sounds/tools from other codebases
  8. Banned content
  9. A word on Git

Reporting Issues

If you ever encounter a bug in-game, the best way to let a coder know about it is with our GitHub Issue Tracker. Please make sure you use the supplied issue template, and include the round ID for the server.

(If you don't have an account, making a new one takes only one minute.)

If you have difficulty, ask for help in the #coding-general channel on our discord.

Introduction

Hello and welcome to /tg/station's contributing page. You are here because you are curious or interested in contributing - thank you! Everyone is free to contribute to this project as long as they follow the simple guidelines and specifications below; at /tg/station, we strive to maintain code stability and maintainability, and to do that, we need all pull requests to hold up to those specifications. It's in everyone's best interests - including yours! - if the same bug doesn't have to be fixed twice because of duplicated code.

First things first, we want to make it clear how you can contribute (if you've never contributed before), as well as the kinds of powers the team has over your additions, to avoid any unpleasant surprises if your pull request is closed for a reason you didn't foresee.

Getting Started

/tg/station doesn't have a list of goals and features to add; we instead allow freedom for contributors to suggest and create their ideas for the game. That doesn't mean we aren't determined to squash bugs, which unfortunately pop up a lot due to the deep complexity of the game. Here are some useful starting guides, if you want to contribute or if you want to know what challenges you can tackle with zero knowledge about the game's code structure.

If you want to contribute the first thing you'll need to do is set up Git so you can download the source code. After setting it up, optionally navigate your git commandline to the project folder and run the command: git config blame.ignoreRevsFile .git-blame-ignore-revs.

We have a list of guides on the wiki that will help you get started contributing to /tg/station with Git and Dream Maker. For beginners, it is recommended you work on small projects like bugfixes at first. If you need help learning to program in BYOND, check out this repository of resources.

There is an open list of approachable issues for your inspiration here.

You can of course, as always, ask for help on the Discord channels or the forums. We're just here to have fun and help out, so please don't expect professional support.

Meet the Team

Headcoder

The Headcoder is responsible for controlling, adding, and removing maintainers from the project. In addition to filling the role of a normal maintainer, they have sole authority on who becomes a maintainer, as well as who remains a maintainer and who does not.

Maintainers

Maintainers are quality control. If a proposed pull request doesn't meet the following specifications, they can request you to change it, or simply just close the pull request. Maintainers are required to give a reason for closing the pull request.

Maintainers can revert your changes if they feel they are not worth maintaining or if they did not live up to the quality specifications.

Maintainer Guidelines

These are the few directives we have for project maintainers.

  • Do not merge PRs you create.
  • Do not merge PRs until 24 hours have passed since it was opened. Exceptions include:
    • Emergency fixes.
      • Try to get secondary maintainer approval before merging if you are able to.
    • PRs with empty commits intended to generate a changelog.
  • Do not merge PRs that contain content from the banned content list.

These are not steadfast rules as maintainers are expected to use their best judgement when operating.

Our team is entirely voluntary, as such we extend our thanks to maintainers, issue managers, and contributors alike for helping keep the project alive.

Issue Managers

Issue Managers help out the project by labelling bug reports and PRs and closing bug reports which are duplicates or are no longer applicable.

What You Can and Can't Do as an Issue Manager

This should help you understand what you can and can't do with your newfound github permissions.

Things you CAN do:

  • Label issues appropriately
  • Close issues when appropriate
  • Label PRs when appropriate

Things you CAN'T do:

  • Close PRs: Only maintainers are allowed to close PRs. Do not hit that button.

Specifications

As mentioned before, you are expected to follow these specifications in order to make everyone's lives easier. It'll save both your time and ours, by making sure you don't have to make any changes and we don't have to ask you to. Thank you for reading this section!

Object Oriented Code

As BYOND's Dream Maker (henceforth "DM") is an object-oriented language, code must be object-oriented when possible in order to be more flexible when adding content to it. If you don't know what "object-oriented" means, we highly recommend you do some light research to grasp the basics.

All BYOND paths must contain the full path

(i.e. absolute pathing)

DM will allow you nest almost any type keyword into a block, such as:

// Not our style!
datum
	datum1
		var
			varname1 = 1
			varname2
			static
				varname3
				varname4
		proc
			proc1()
				code
			proc2()
				code

		datum2
			varname1 = 0
			proc
				proc3()
					code
			proc2()
				. = ..()
				code

The use of this is not allowed in this project as it makes finding definitions via full text searching next to impossible. The only exception is the variables of an object may be nested to the object, but must not nest further.

The previous code made compliant:

// Matches /tg/station style.
/datum/datum1
	var/varname1
	var/varname2
	var/static/varname3
	var/static/varname4

/datum/datum1/proc/proc1()
	code
/datum/datum1/proc/proc2()
	code
/datum/datum1/datum2
	varname1 = 0
/datum/datum1/datum2/proc/proc3()
	code
/datum/datum1/datum2/proc2()
	. = ..()
	code

All process procs need to make use of delta-time and be frame independent

In a lot of our older code, process() is frame dependent. Here's some example mob code:

/mob/testmob
	var/health = 100
	var/health_loss = 4 //We want to lose 2 health per second, so 4 per SSmobs process

/mob/testmob/process(delta_time) //SSmobs runs once every 2 seconds
	health -= health_loss

As the mobs subsystem runs once every 2 seconds, the mob now loses 4 health every process, or 2 health per second. This is called frame dependent programming.

Why is this an issue? If someone decides to make it so the mobs subsystem processes once every second (2 times as fast), your effects in process() will also be two times as fast. Resulting in 4 health loss per second rather than 2.

How do we solve this? By using delta-time. Delta-time is the amount of seconds you would theoretically have between 2 process() calls. In the case of the mobs subsystem, this would be 2 (As there is 2 seconds between every call in process()). Here is a new example using delta-time:

/mob/testmob
	var/health = 100
	var/health_loss = 2 //Health loss every second

/mob/testmob/process(delta_time) //SSmobs runs once every 2 seconds
	health -= health_loss * delta_time

In the above example, we made our health_loss variable a per second value rather than per process. In the actual process() proc we then make use of deltatime. Because SSmobs runs once every 2 seconds. Delta_time would have a value of 2. This means that by doing health_loss * delta_time, you end up with the correct amount of health_loss per process, but if for some reason the SSmobs subsystem gets changed to be faster or slower in a PR, your health_loss variable will work the same.

For example, if SSmobs is set to run once every 4 seconds, it would call process once every 4 seconds and multiply your health_loss var by 4 before subtracting it. Ensuring that your code is frame independent.

No overriding type safety checks

The use of the : operator to override type safety checks is not allowed. You must cast the variable to the proper type.

Type paths must begin with a /

eg: /datum/thing, not datum/thing

Type paths must be snake case

eg: /datum/blue_bird, not /datum/BLUEBIRD or /datum/BlueBird or /datum/Bluebird or /datum/blueBird

Datum type paths must began with "datum"

In DM, this is optional, but omitting it makes finding definitions harder.

Do not use text/string based type paths

It is rarely allowed to put type paths in a text format, as there are no compile errors if the type path no longer exists. Here is an example:

//Good
var/path_type = /obj/item/baseball_bat

//Bad
var/path_type = "/obj/item/baseball_bat"

Use var/name format when declaring variables

While DM allows other ways of declaring variables, this one should be used for consistency.

Tabs, not spaces

You must use tabs to indent your code, NOT SPACES.

Do not use tabs/spaces for indentation in the middle of a code line. Not only is this inconsistent because the size of a tab is undefined, but it means that, should the line you're aligning to change size at all, we have to adjust a ton of other code. Plus, it often time hurts readability.

// Bad
#define SPECIES_MOTH			"moth"
#define SPECIES_LIZARDMAN		"lizardman"
#define SPECIES_FELINID			"felinid"

// Good
#define SPECIES_MOTH "moth"
#define SPECIES_LIZARDMAN "lizardman"
#define SPECIES_FELINID "felinid"

No hacky code

Hacky code, such as adding specific checks, is highly discouraged and only allowed when there is no other option. (Protip: "I couldn't immediately think of a proper way so thus there must be no other option" is not gonna cut it here! If you can't think of anything else, say that outright and admit that you need help with it. Maintainers exist for exactly that reason.)

You can avoid hacky code by using object-oriented methodologies, such as overriding a function (called "procs" in DM) or sectioning code into functions and then overriding them as required.

No duplicated code

Copying code from one place to another may be suitable for small, short-time projects, but /tg/station is a long-term project and highly discourages this.

Instead you can use object orientation, or simply placing repeated code in a function, to obey this specification easily.

Startup/Runtime tradeoffs with lists and the "hidden" init proc

First, read the comments in this BYOND thread, starting where the link takes you.

There are two key points here:

  1. Defining a list in the variable's definition calls a hidden proc - init. If you have to define a list at startup, do so in New() (or preferably Initialize()) and avoid the overhead of a second call (Init() and then New())

  2. It also consumes more memory to the point where the list is actually required, even if the object in question may never use it!

Remember: although this tradeoff makes sense in many cases, it doesn't cover them all. Think carefully about your addition before deciding if you need to use it.

Prefer Initialize() over New() for atoms

Our game controller is pretty good at handling long operations and lag, but it can't control what happens when the map is loaded, which calls New for all atoms on the map. If you're creating a new atom, use the Initialize proc to do what you would normally do in New. This cuts down on the number of proc calls needed when the world is loaded. See here for details on Initialize: https://github.com/tgstation/tgstation/blob/34775d42a2db4e0f6734560baadcfcf5f5540910/code/game/atoms.dm#L166 While we normally encourage (and in some cases, even require) bringing out of date code up to date when you make unrelated changes near the out of date code, that is not the case for New -> Initialize conversions. These systems are generally more dependant on parent and children procs so unrelated random conversions of existing things can cause bugs that take months to figure out.

No magic numbers or strings

This means stuff like having a "mode" variable for an object set to "1" or "2" with no clear indicator of what that means. Make these #defines with a name that more clearly states what it's for. For instance:

/datum/proc/do_the_thing(thing_to_do)
	switch(thing_to_do)
		if(1)
			(...)
		if(2)
			(...)

There's no indication of what "1" and "2" mean! Instead, you'd do something like this:

#define DO_THE_THING_REALLY_HARD 1
#define DO_THE_THING_EFFICIENTLY 2
/datum/proc/do_the_thing(thing_to_do)
	switch(thing_to_do)
		if(DO_THE_THING_REALLY_HARD)
			(...)
		if(DO_THE_THING_EFFICIENTLY)
			(...)

This is clearer and enhances readability of your code! Get used to doing it!

Control statements

(if, while, for, etc)

  • No control statement may contain code on the same line as the statement (if (blah) return)
  • All control statements comparing a variable to a number should use the formula of thing operator number, not the reverse (eg: if (count <= 10) not if (10 >= count))

Use early return

Do not enclose a proc in an if-block when returning on a condition is more feasible This is bad:

/datum/datum1/proc/proc1()
	if (thing1)
		if (!thing2)
			if (thing3 == 30)
				do stuff

This is good:

/datum/datum1/proc/proc1()
	if (!thing1)
		return
	if (thing2)
		return
	if (thing3 != 30)
		return
	do stuff

This prevents nesting levels from getting deeper then they need to be.

Use our time defines

The codebase contains some defines which will automatically multiply a number by the correct amount to get a number in deciseconds. Using these is preffered over using a literal amount in deciseconds.

The defines are as follows:

  • SECONDS
  • MINUTES
  • HOURS

This is bad:

/datum/datum1/proc/proc1()
	if(do_after(mob, 15))
		mob.dothing()

This is good:

/datum/datum1/proc/proc1()
	if(do_after(mob, 1.5 SECONDS))
		mob.dothing()

Getters and setters

  • Avoid getter procs. They are useful tools in languages with that properly enforce variable privacy and encapsulation, but DM is not one of them. The upfront cost in proc overhead is met with no benefits, and it may tempt to develop worse code.

This is bad:

/datum/datum1/proc/simple_getter()
	return gotten_variable

Prefer to either access the variable directly or use a macro/define.

  • Make usage of variables or traits, set up through condition setters, for a more maintainable alternative to compex and redefined getters.

These are bad:

/datum/datum1/proc/complex_getter()
	return condition ? VALUE_A : VALUE_B

/datum/datum1/child_datum/complex_getter()
	return condition ? VALUE_C : VALUE_D

This is good:

/datum/datum1
	var/getter_turned_into_variable

/datum/datum1/proc/set_condition(new_value)
	if(condition == new_value)
		return
	condition = new_value
	on_condition_change()

/datum/datum1/proc/on_condition_change()
	getter_turned_into_variable = condition ? VALUE_A : VALUE_B

/datum/datum1/child_datum/on_condition_change()
	getter_turned_into_variable = condition ? VALUE_C : VALUE_D

Avoid unnecessary type checks and obscuring nulls in lists

Typecasting in for loops carries an implied istype() check that filters non-matching types, nulls included. The as anything key can be used to skip the check.

If we know the list is supposed to only contain the desired type then we want to skip the check not only for the small optimization it offers, but also to catch any null entries that may creep into the list.

Nulls in lists tend to point to improperly-handled references, making hard deletes hard to debug. Generating a runtime in those cases is more often than not positive.

This is bad:

var/list/bag_of_atoms = list(new /obj, new /mob, new /atom, new /atom/movable, new /atom/movable)
var/highest_alpha = 0
for(var/atom/thing in bag_of_atoms)
	if(thing.alpha <= highest_alpha)
		continue
	highest_alpha = thing.alpha

This is good:

var/list/bag_of_atoms = list(new /obj, new /mob, new /atom, new /atom/movable, new /atom/movable)
var/highest_alpha = 0
for(var/atom/thing as anything in bag_of_atoms)
	if(thing.alpha <= highest_alpha)
		continue
	highest_alpha = thing.alpha

Develop Secure Code

  • Player input must always be escaped safely, we recommend you use stripped_input in all cases where you would use input. Essentially, just always treat input from players as inherently malicious and design with that use case in mind

  • Calls to the database must be escaped properly - use sanitizeSQL to escape text based database entries from players or admins, and isnum() for number based database entries from players or admins.

  • All calls to topics must be checked for correctness. Topic href calls can be easily faked by clients, so you should ensure that the call is valid for the state the item is in. Do not rely on the UI code to provide only valid topic calls, because it won't.

  • Information that players could use to metagame (that is, to identify round information and/or antagonist type via information that would not be available to them in character) should be kept as administrator only.

  • It is recommended as well you do not expose information about the players - even something as simple as the number of people who have readied up at the start of the round can and has been used to try to identify the round type.

  • Where you have code that can cause large-scale modification and FUN, make sure you start it out locked behind one of the default admin roles - use common sense to determine which role fits the level of damage a function could do.

Files

  • Because runtime errors do not give the full path, try to avoid having files with the same name across folders.

  • File names should not be mixed case, or contain spaces or any character that would require escaping in a uri.

  • Files and path accessed and referenced by code above simply being #included should be strictly lowercase to avoid issues on filesystems where case matters.

SQL

  • Do not use the shorthand sql insert format (where no column names are specified) because it unnecessarily breaks all queries on minor column changes and prevents using these tables for tracking outside related info such as in a connected site/forum.

  • All changes to the database's layout(schema) must be specified in the database changelog in SQL, as well as reflected in the schema files

  • Any time the schema is changed the schema_revision table and DB_MAJOR_VERSION or DB_MINOR_VERSION defines must be incremented.

  • Queries must never specify the database, be it in code, or in text files in the repo.

  • Primary keys are inherently immutable and you must never do anything to change the primary key of a row or entity. This includes preserving auto increment numbers of rows when copying data to a table in a conversion script. No amount of bitching about gaps in ids or out of order ids will save you from this policy.

  • The ttl for data from the database is 10 seconds. You must have a compelling reason to store and reuse data for longer then this.

  • Do not write stored and transformed data to the database, instead, apply the transformation to the data in the database directly.

    • ie: SELECTing a number from the database, doubling it, then updating the database with the doubled number. If the data in the database changed between step 1 and 3, you'll get an incorrect result. Instead, directly double it in the update query. UPDATE table SET num = num*2 instead of UPDATE table SET num = [num].
    • if the transformation is user provided (such as allowing a user to edit a string), you should confirm the value being updated did not change in the database in the intervening time before writing the new user provided data by checking the old value with the current value in the database, and if it has changed, allow the user to decide what to do next.

Mapping Standards

  • Adding, Removing, or Replacing Station Maps

    • All pull requests adding, removing, or replacing station maps must receive prior approval from a maptainer, or they will be closed without additional warning.

  • TGM Format & Map Merge

    • All new maps submitted to the repo through a pull request must be in TGM format (unless there is a valid reason present to have it in the default BYOND format). This is done using the Map Merge utility included in the repo to convert the file to TGM format.
    • Likewise, you MUST run Map Merge prior to opening your PR when updating existing maps to minimize the change differences (even when using third party mapping programs such as FastDMM.)
      • Failure to run Map Merge on a map after using third party mapping programs (such as FastDMM) greatly increases the risk of the map's key dictionary becoming corrupted by future edits after running map merge. Resolving the corruption issue involves rebuilding the map's key dictionary; id est rewriting all the keys contained within the map by reconverting it from BYOND to TGM format - which creates very large differences that ultimately delay the PR process and is extremely likely to cause merge conflicts with other pull requests.

  • Variable Editing (Var-edits)

    • While var-editing an item within the editor is perfectly fine, it is preferred that when you are changing the base behavior of an item (how it functions) that you make a new subtype of that item within the code, especially if you plan to use the item in multiple locations on the same map, or across multiple maps. This makes it easier to make corrections as needed to all instances of the item at one time as opposed to having to find each instance of it and change them all individually.
      • Subtypes only intended to be used on away mission or ruin maps should be contained within a .dm file with a name corresponding to that map within code\modules\awaymissions or code\modules\ruins respectively. This is so in the event that the map is removed, that subtype will be removed at the same time as well to minimize leftover/unused data within the repo.
    • Please attempt to clean out any dirty variables that may be contained within items you alter through var-editing. For example, due to how DM functions, changing the pixel_x variable from 23 to 0 will leave a dirty record in the map's code of pixel_x = 0. Likewise this can happen when changing an item's icon to something else and then back. This can lead to some issues where an item's icon has changed within the code, but becomes broken on the map due to it still attempting to use the old entry.
    • Areas should not be var-edited on a map to change it's name or attributes. All areas of a single type and it's altered instances are considered the same area within the code, and editing their variables on a map can lead to issues with powernets and event subsystems which are difficult to debug.

User Interfaces

Signal Handlers

All procs that are registered to listen for signals using RegisterSignal() must contain at the start of the proc SIGNAL_HANDLER eg;

/type/path/proc/signal_callback()
	SIGNAL_HANDLER
	// rest of the code

This is to ensure that it is clear the proc handles signals and turns on a lint to ensure it does not sleep.

Any sleeping behaviour that you need to perform inside a SIGNAL_HANDLER proc must be called asynchronously (e.g. with INVOKE_ASYNC()) or be redone to work asynchronously.

Enforcing parent calling

When adding new signals to root level procs, eg;

/atom/proc/setDir(newdir)
	SHOULD_CALL_PARENT(TRUE)
	SEND_SIGNAL(src, COMSIG_ATOM_DIR_CHANGE, dir, newdir)
	dir = newdir

The SHOULD_CALL_PARENT(TRUE) lint should be added to ensure that overrides/child procs call the parent chain and ensure the signal is sent.

Use descriptive and obvious names

Optimize for readability, not writability. While it is certainly easier to write M than victim, it will cause issues down the line for other developers to figure out what exactly your code is doing, even if you think the variable's purpose is obvious.

Don't use abbreviations

Avoid variables like C, M, and H. Prefer names like "user", "victim", "weapon", etc.

// What is M? The user? The target?
// What is A? The target? The item?
/proc/use_item(mob/M, atom/A)

// Much better!
/proc/use_item(mob/user, atom/target)

Unless it is otherwise obvious, try to avoid just extending variables like "C" to "carbon"--this is slightly more helpful, but does not describe the context of the use of the variable.

Naming things when typecasting

When typecasting, keep your names descriptive:

var/mob/living/living_target = target
var/mob/living/carbon/carbon_target = living_target

Of course, if you have a variable name that better describes the situation when typecasting, feel free to use it.

Note that it's okay, semantically, to use the same variable name as the type, e.g.:

var/atom/atom
var/client/client
var/mob/mob

Your editor may highlight the variable names, but BYOND, and we, accept these as variable names:

// This functions properly!
var/client/client = CLIENT_FROM_VAR(usr)
// vvv this may be highlighted, but it's fine!
client << browse(...)

Name things as directly as possible

was_called is better than has_been_called. notify is better than do_notification.

Avoid negative variable names

is_flying is better than is_not_flying. late is better than not_on_time. This prevents double-negatives (such as if (!is_not_flying) which can make complex checks more difficult to parse.

Exceptions to variable names

Exceptions can be made in the case of inheriting existing procs, as it makes it so you can use named parameters, but new variable names must follow these standards. It is also welcome, and encouraged, to refactor existing procs to use clearer variable names.

Naming numeral iterator variables i is also allowed, but do remember to Avoid unnecessary type checks and obscuring nulls in lists, and making more descriptive variables is always encouraged.

// Bad
for (var/datum/reagent/R as anything in reagents)

// Good
for (var/datum/reagent/deadly_reagent as anything in reagents)

// Allowed, but still has the potential to not be clear. What does `i` refer to?
for (var/i in 1 to 12)

// Better
for (var/month in 1 to 12)

// Bad, only use `i` for numeral loops
for (var/i in reagents)

Icons are for image manipulation and defining an obj's .icon var, appearances are for everything else.

BYOND will allow you to use a raw icon file or even an icon datum for underlays, overlays, and what not (you can even use strings to refer to an icon state on the current icon). The issue is these get converted by BYOND to appearances on every overlay insert or removal involving them, and this process requires inserting the new appearance into the global list of appearances, and informing clients about them.

Converting them yourself to appearances and storing this converted value will ensure this process only has to happen once for the lifetime of the round. Helper functions exist to do most of the work for you.

Bad:

/obj/machine/update_overlays(blah)
	if (stat & broken)
		add_overlay(icon(broken_icon))  //this icon gets created, passed to byond, converted to an appearance, then deleted.
		return
	if (is_on)
		add_overlay("on") //also bad, the converstion to an appearance still has to happen
	else
		add_overlay(iconstate2appearance(icon, "off")) //this might seem alright, but not storing the value just moves the repeated appearance generation to this proc rather then the core overlay management. It would only be acceptable (and to some degree perferred) if this overlay is only ever added once (like in init code)

Good:

/obj/machine/update_overlays(var/blah)
	var/static/on_overlay
	var/static/off_overlay
	var/static/broken_overlay
	if(isnull(on_overlay)) //static vars initialize with global variables, meaning src is null and this won't pass integration tests unless you check.
		on_overlay = iconstate2appearance(icon, "on")
		off_overlay = iconstate2appearance(icon, "off")
		broken_overlay = icon2appearance(broken_icon)
	if (stat & broken)
		add_overlay(broken_overlay) 
		return
	if (is_on)
		add_overlay(on_overlay)
	else
		add_overlay(off_overlay)
	...

Note: images are appearances with extra steps, and don't incur the overhead in conversion.

Do not abuse associated lists.

Associated lists that could instead be variables or statically defined number indexed lists will use more memory, as associated lists have a 24 bytes per item overhead (vs 8 for lists and most vars), and are slower to search compared to static/global variables and lists with known indexes.

Bad:

/obj/machine/update_overlays(var/blah)
	var/static/our_overlays
	if(isnull(our_overlays)
		our_overlays = list("on" = iconstate2appearance(overlay_icon, "on"), "off" = iconstate2appearance(overlay_icon, "off"), "broken" = iconstate2appearance(overlay_icon, "broken"))
	if (stat & broken)
		add_overlay(our_overlays["broken"]) 
		return
	...

Good:

#define OUR_ON_OVERLAY 1
#define OUR_OFF_OVERLAY 2
#define OUR_BROKEN_OVERLAY 3
/obj/machine/update_overlays(var/blah
	var/static/our_overlays
	if(isnull(our_overlays)
		our_overlays = list(iconstate2appearance(overlay_icon, "on"), iconstate2appearance(overlay_icon, "off"), iconstate2appearance(overlay_icon, "broken"))
	if (stat & broken)
		add_overlay(our_overlays[OUR_BROKEN_OVERLAY])
		return
	...

#undef OUR_ON_OVERLAY
#undef OUR_OFF_OVERLAY
#undef OUR_BROKEN_OVERLAY

Storing these in a flat (non-associated) list saves on memory, and using defines to reference locations in the list saves CPU time searching the list.

Also good:

/obj/machine/update_overlays(var/blah)
	var/static/on_overlay
	var/static/off_overlay
	var/static/broken_overlay
	if(isnull(on_overlay))
		on_overlay = iconstate2appearance(overlay_icon, "on")
		off_overlay = iconstate2appearance(overlay_icon, "off")
		broken_overlay = iconstate2appearance(overlay_icon, "broken")
	if (stat & broken)
		add_overlay(broken_overlay)
		return
	...

Proc variables, static variables, and global variables are resolved at compile time, so the above is equivalent to the second example, but is easier to read, and avoids the need to store a list.

Note: While there has historically been a strong impulse to use associated lists for caching of computed values, this is the easy way out and leaves a lot of hidden overhead. Please keep this in mind when designing core/root systems that are intended for use by other code/coders. It's normally better for consumers of such systems to handle their own caching using vars and number indexed lists, than for you to do it using associated lists.

When passing vars through New() or Initialize()'s arguments, use src.var

Using src.var + naming the arguments the same as the var is the most readable and intuitive way to pass arguments into a new instance's vars. The main benefit is that you do not need to give arguments odd names with prefixes and suffixes that are easily forgotten in new() when sending named args.

This is very bad:

/atom/thing
	var/is_red

/atom/thing/Initialize(mapload, enable_red)
	is_red = enable_red

/proc/make_red_thing()
	new /atom/thing(null, enable_red = TRUE)

Future coders using this code will have to remember two differently named variables which are near-synonyms of eachother. One of them is only used in Initialize for one line.

This is bad:

/atom/thing
	var/is_red

/atom/thing/Initialize(mapload, _is_red)
	is_red = _is_red

/proc/make_red_thing()
	new /atom/thing(null, _is_red = TRUE)

_is_red is being used to set is_red and yet means a random '_' needs to be appended to the front of the arg, same as all other args like this.

This is good:

/atom/thing
	var/is_red

/atom/thing/Initialize(mapload, is_red)
	src.is_red = is_red

/proc/make_red_thing()
	new /atom/thing(null, is_red = TRUE)

Setting is_red in args is simple, and directly names the variable the argument sets.

Other Notes

  • Code should be modular where possible; if you are working on a new addition, then strongly consider putting it in its own file unless it makes sense to put it with similar ones (i.e. a new tool would go in the "tools.dm" file)

  • Bloated code may be necessary to add a certain feature, which means there has to be a judgement over whether the feature is worth having or not. You can help make this decision easier by making sure your code is modular.

  • You are expected to help maintain the code that you add, meaning that if there is a problem then you are likely to be approached in order to fix any issues, runtimes, or bugs.

  • Do not divide when you can easily convert it to multiplication. (ie 4/2 should be done as 4*0.5)

  • Separating single lines into more readable blocks is not banned, however you should use it only where it makes new information more accessible, or aids maintainability. We do not have a column limit, and mass conversions will not be received well.

  • If you used regex to replace code during development of your code, post the regex in your PR for the benefit of future developers and downstream users.

  • Changes to the /config tree must be made in a way that allows for updating server deployments while preserving previous behaviour. This is due to the fact that the config tree is to be considered owned by the user and not necessarily updated alongside the remainder of the code. The code to preserve previous behaviour may be removed at some point in the future given the OK by maintainers.

  • The dlls section of tgs3.json is not designed for dlls that are purely call()()ed since those handles are closed between world reboots. Only put in dlls that may have to exist between world reboots.

Enforced not enforced

The following coding styles are not only not enforced at all, but are generally frowned upon to change for little to no reason:

  • English/British spelling on var/proc names
    • Color/Colour - both are fine, but keep in mind that BYOND uses color as a base variable
  • Spaces after control statements
    • if() and if () - nobody cares!

Operators

Spacing

(this is not strictly enforced, but more a guideline for readability's sake)

  • Operators that should be separated by spaces
    • Boolean and logic operators like &&, || <, >, ==, etc (but not !)
    • Bitwise AND &
    • Argument separator operators like , (and ; when used in a forloop)
    • Assignment operators like = or += or the like
  • Operators that should not be separated by spaces
    • Bitwise OR |
    • Access operators like . and :
    • Parentheses ()
    • logical not !

Math operators like +, -, /, *, etc are up in the air, just choose which version looks more readable.

Use

  • Bitwise AND - '&'
    • Should be written as variable & CONSTANT NEVER CONSTANT & variable. Both are valid, but the latter is confusing and nonstandard.
  • Associated lists declarations must have their key value quoted if it's a string
    • WRONG: list(a = "b")
    • RIGHT: list("a" = "b")

Dream Maker Quirks/Tricks

Like all languages, Dream Maker has its quirks, some of them are beneficial to us, like these

In-To for-loops

for(var/i = 1, i <= some_value, i++) is a fairly standard way to write an incremental for loop in most languages (especially those in the C family), but DM's for(var/i in 1 to some_value) syntax is oddly faster than its implementation of the former syntax; where possible, it's advised to use DM's syntax. (Note, the to keyword is inclusive, so it automatically defaults to replacing <=; if you want < then you should write it as 1 to some_value-1).

HOWEVER, if either some_value or i changes within the body of the for (underneath the for(...) header) or if you are looping over a list AND changing the length of the list then you can NOT use this type of for-loop!

for(var/A in list) versus for(var/i in 1 to list.len)

The former is faster than the latter, as shown by the following profile results: https://file.house/zy7H.png Code used for the test in a readable format: https://pastebin.com/w50uERkG

Dot variable

Like other languages in the C family, DM has a . or "Dot" operator, used for accessing variables/members/functions of an object instance. eg:

var/mob/living/carbon/human/H = YOU_THE_READER
H.gib()

However, DM also has a dot variable, accessed just as . on its own, defaulting to a value of null. Now, what's special about the dot operator is that it is automatically returned (as in the return statement) at the end of a proc, provided the proc does not already manually return (return count for example.) Why is this special?

With . being everpresent in every proc, can we use it as a temporary variable? Of course we can! However, the . operator cannot replace a typecasted variable - it can hold data any other var in DM can, it just can't be accessed as one, although the . operator is compatible with a few operators that look weird but work perfectly fine, such as: .++ for incrementing .'s value, or .[1] for accessing the first element of ., provided that it's a list.

Globals versus static

DM has a var keyword, called global. This var keyword is for vars inside of types. For instance:

/mob
	var/global/thing = TRUE

This does NOT mean that you can access it everywhere like a global var. Instead, it means that that var will only exist once for all instances of its type, in this case that var will only exist once for all mobs - it's shared across everything in its type. (Much more like the keyword static in other languages like PHP/C++/C#/Java)

Isn't that confusing?

There is also an undocumented keyword called static that has the same behaviour as global but more correctly describes BYOND's behaviour. Therefore, we always use static instead of global where we need it, as it reduces suprise when reading BYOND code.

Pull Request Process

There is no strict process when it comes to merging pull requests. Pull requests will sometimes take a while before they are looked at by a maintainer; the bigger the change, the more time it will take before they are accepted into the code. Every team member is a volunteer who is giving up their own time to help maintain and contribute, so please be courteous and respectful. Here are some helpful ways to make it easier for you and for the maintainers when making a pull request.

  • Make sure your pull request complies to the requirements outlined here

  • You are expected to have tested your pull requests if it is anything that would warrant testing. Text only changes, single number balance changes, and similar generally don't need testing, but anything else does. This means by extension web edits are disallowed for larger changes.

  • You are going to be expected to document all your changes in the pull request. Failing to do so will mean delaying it as we will have to question why you made the change. On the other hand, you can speed up the process by making the pull request readable and easy to understand, with diagrams or before/after data. Should you be optimizing a routine you must provide proof by way of profiling that your changes are faster.

  • We ask that you use the changelog system to document your player facing changes, which prevents our players from being caught unaware by said changes - you can find more information about this on this wiki page.

  • If you are proposing multiple changes, which change many different aspects of the code, you are expected to section them off into different pull requests in order to make it easier to review them and to deny/accept the changes that are deemed acceptable.

  • If your pull request is accepted, the code you add no longer belongs exclusively to you but to everyone; everyone is free to work on it, but you are also free to support or object to any changes being made, which will likely hold more weight, as you're the one who added the feature. It is a shame this has to be explicitly said, but there have been cases where this would've saved some trouble.

  • Please explain why you are submitting the pull request, and how you think your change will be beneficial to the game. Failure to do so will be grounds for rejecting the PR.

  • If your pull request is not finished, you may open it as a draft for potential review. If you open it as a full-fledged PR make sure it is at least testable in a live environment. Pull requests that do not at least meet this requirement will be closed. You may request a maintainer reopen the pull request when you're ready, or make a new one.

  • While we have no issue helping contributors (and especially new contributors) bring reasonably sized contributions up to standards via the pull request review process, larger contributions are expected to pass a higher bar of completeness and code quality before you open a pull request. Maintainers may close such pull requests that are deemed to be substantially flawed. You should take some time to discuss with maintainers or other contributors on how to improve the changes.

  • After leaving reviews on an open pull request, maintainers may convert it to a draft. Once you have addressed all their comments to the best of your ability, feel free to mark the pull as Ready for Review again.

Porting features/sprites/sounds/tools from other codebases

If you are porting features/tools from other codebases, you must give them credit where it's due. Typically, crediting them in your pull request and the changelog is the recommended way of doing it. Take note of what license they use though, porting stuff from AGPLv3 and GPLv3 codebases are allowed.

Regarding sprites & sounds, you must credit the artist and possibly the codebase. All /tg/station assets including icons and sound are under a Creative Commons 3.0 BY-SA license unless otherwise indicated. However if you are porting assets from GoonStation or usually any assets under the Creative Commons 3.0 BY-NC-SA license are to go into the 'goon' folder of the /tg/station codebase.

Banned content

Do not add any of the following in a Pull Request or risk getting the PR closed:

  • National Socialist Party of Germany content, National Socialist Party of Germany related content, or National Socialist Party of Germany references
  • Code adding, removing, or updating the availability of alien races/species/human mutants without prior approval. Pull requests attempting to add or remove features from said races/species/mutants require prior approval as well.
  • Code which violates GitHub's terms of service.

Just because something isn't on this list doesn't mean that it's acceptable. Use common sense above all else.

A word on Git

This repository uses LF line endings for all code as specified in the .gitattributes and .editorconfig files.

Unless overridden or a non standard git binary is used the line ending settings should be applied to your clone automatically.

Note: VSC requires an extension to take advantage of editorconfig.