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Coding Requirements

Coders 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.

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.

Use absolute pathing

DM will allow you nest almost any type keyword into a block, as in the following:

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 format 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:

/datum/datum1
    var/varname1 = 1
    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

Do not compare boolean values to TRUE or FALSE

Do not compare boolean values to TRUE or FALSE. For TRUE you should just check if there’s a value in that address. For FALSE you should use the ! operator. An exception is made to this when working with JavaScript or other external languages. If a function/variable can contain more values beyond null or 0 or TRUE, use numbers and defines instead of true/false comparisons.

// Bad
var/thing = pick(TRUE, FALSE)
if(thing == TRUE)
    return "bleh"
var/other_thing = pick(TRUE, FALSE)
if(other_thing == FALSE)
    return "meh"

// Good
var/thing = pick(TRUE, FALSE)
if(thing)
    return "bleh"
var/other_thing = pick(TRUE, FALSE)
if(!other_thing)
    return "meh"

Use pick(x, y, z), not pick(list(x, y, z))

pick() takes a fixed set of options. Wrapping them in a list is redundant and slightly less efficient.

// Bad
var/text = pick(list("test_1", "test_2", "test_3"))
to_chat(world, text)

// Good
var/text = pick("test_1", "test_2", "test_3")
to_chat(world, text)

User Interfaces

All new user interfaces in the game must be created using the TGUI framework. Documentation can be found inside the tgui/docs folder, and the README.md file. This is to ensure all ingame UIs are snappy and responsive. An exception is made for user interfaces which are purely for OOC actions (Such as character creation, or anything admin related)

No overriding type safety checks

The use of the : “runtime search” operator to override type safety checks is not allowed. Variables must be casted to the proper type.

Do not chain proc calls and variable access

The use of the pointer operator, ., should not be used to access the return values of functions directly. This can cause unintended behavior and is difficult to read.

//Bad
var/our_x = get_turf(thing).x

//Good
var/turf/our_turf = get_turf(thing)
var/our_x = our_turf.x

Type paths must begin with a /

e.g.: /datum/thing, not datum/thing

Datum type paths must began with “datum”

In DM, this is optional, but omitting it makes finding definitions harder. To be specific, you can declare the path /arbitrary, but it will still be, in actuality, /datum/arbitrary. Write your code to reflect this.

Do not use list operators in strings

The use of list operators to augment strings is not allowed. This is roughly 10 times slower than using a list with a Join() Function.

//Bad
var/text = "text"
text += "More text"
to_chat(world, text)

//Good
var/list/text = list("text")
text += "More text"
to_chat(world, text.Join(""))

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:

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

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

Do not use \The

The \The macro doesn’t actually do anything when used in the format \The [atom reference]. Directly referencing an atom in an embedded string will automatically prefix The or the to it as appropriate. As an extension, when referencing an atom, don’t use [atom.name], use [atom]. The only exception to this rule is when dealing with items “belonging” to a mob, in which case you should use [mob]'s [atom.name] to avoid The ever forming.

//Bad
var/atom/A
"\The [A]"

//Good
var/atom/A
"[A]"

Use the pronoun library instead of \his macros

We have a system in code/__HELPERS/pronouns.dm for addressing all forms of pronouns. This is useful in a number of ways;

  • BYOND’s \his macro can be unpredictable on what object it references. Take this example: "[user] waves \his [user.weapon] around, hitting \his opponents!". This will end up referencing the user’s gender in the first occurrence, but what about the second? It’ll actually print the gender set on the weapon he’s carrying, which is unintended - and there’s no way around this.
  • It always prints the real gender variable of the atom it’s referencing. This can lead to exposing a mob’s gender even when their face is covered, which would normally prevent it’s gender from being printed.

The way to avoid these problems is to use the pronoun system. Instead of "[user] waves \his arms.", you can do "[user] waves [user.p_their()] arms."

//Bad
"[H] waves \his hands!"
"[user] waves \his [user.weapon] around, hitting \his opponents!"

//Good
"[H] waves [H.p_their()] hands!"
"[user] waves [H.p_their()] [user.weapon] around, hitting [H.p_their()] opponents!"`

Use [A.UID()] over \ref[A]

BYOND has a system to pass “soft references” to datums, using the format "\ref[datum]" inside a string. This allows you to find the object just based off of a text string, which is especially useful when dealing with the bridge between BYOND code and HTML/JS in UIs. It’s resolved back into an object reference by using locate("\ref[datum]") when the code comes back to BYOND. The issue with this is that locate() can return a unexpected datum if the original datum has been deleted - BYOND recycles the references.

UID’s are actually unique; they work off of a global counter and are not recycled. Each datum has one assigned to it when it’s created, which can be accessed by [datum.UID()]. You can use this as a snap-in replacement for \ref by changing any locate(ref) calls in your code to locateUID(ref). Usage of this system is mandatory for any Topic() calls, and will produce errors in Dream Daemon if it’s not used.

//Bad
"<a href='byond://?src=\ref[src];'>Link!</a>"

//Good
"<a href='byond://?src=[UID()];'>Link!</a>"

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. You may use spaces to align text, but you should tab to the block level first, then add the remaining spaces.

No hacky code

Hacky code, such as adding specific checks (ex: istype(src, /obj/whatever)), is highly discouraged and only allowed when there is no other option. (Pro-tip: ‘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, PR Reviewers, and other contributors who can help you 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.

The same also applies to bugfixes - If an invalid value is being passed into a proc from something that shouldn’t have that value, don’t fix it on the proc itself, fix it at its origin! (Where feasible)

No duplicated code

Copying code from one place to another may be suitable for small, short-time projects, but Paradise 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.

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 dependent on parent and children procs, so unrelated random conversions of existing things can cause bugs that take months to figure out.

No implicit var/

When you declare a parameter in a proc, the var/ is implicit. Do not include any implicit var/ when declaring a variable.

//Bad
/obj/item/proc1(var/mob/input1, var/input2)
    code

//Good
/obj/item/proc1(mob/input1, input2)
    code

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:

//Bad
/datum/proc/do_the_thing(thing_to_do)
    switch(thing_to_do)
        if(1)
            do_stuff()
        if(2)
            do_other_stuff()

There’s no indication of what “1” and “2” mean! Instead, you should do something like this:

//Good
#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)
            do_stuff()
        if(DO_THE_THING_EFFICIENTLY)
            do_other_stuff()

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

Control statements

  • All control statements comparing a variable to a number should use the formula of thing operator number, not the reverse (e.g. if(count <= 10) not if(10 >= count))
  • All control statements must be spaced as if(), with the brackets touching the keyword.
  • All control statements must not contain code on the same line as the statement.
//Bad
if(x) return

//Good
if(x)
    return

Player Output

Due to the use of “TGchat”, Paradise requires a special syntax for outputting text messages to players. Instead of mob << "message", you must use to_chat(mob, "message"). Failure to do so will lead to your code not working.

Use guard clauses

Guard clauses are early returns in a proc for specific conditions. This is preferred wrapping most of a proc’s behavior in an in-block, as procs will often check a handful of early conditions to bail out on.

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 addtimer() instead of sleep() or spawn()

If you need to call a proc after a set amount of time, use addtimer() instead of spawn() / sleep() where feasible. Though more complex, this method has greater performance. Additionally, unlike spawn() or sleep(), it can be cancelled. For more details, see https://github.com/tgstation/tgstation/pull/22933.

Look for code examples on how to properly use it.

//Bad
/datum/datum1/proc/proc1(target)
    spawn(5 SECONDS)
    target.dothing(arg1, arg2, arg3)

//Good
/datum/datum1/proc/proc1(target)
    addtimer(CALLBACK(target, PROC_REF(dothing), arg1, arg2, arg3), 5 SECONDS)

Signals

Signals are a slightly more advanced topic, but are often useful for attaching external behavior to objects that should be triggered when a specific event occurs.

When defining procs that should be called by signals, you must include SIGNAL_HANDLER after the proc header. This ensures that no sleeping code can be called from within a signal handler, as that can cause problems with the signal system.

Since callbacks can be connected to many signals with RegisterSignal, it can be difficult to pin down the source that a callback is invoked from. Any new SIGNAL_HANDLER should be followed by a comment listing the signals that the proc is expected to be invoked for. If there are multiple signals to be handled, separate them with a +.

/atom/movable/proc/when_moved(atom/movable/A)
    SIGNAL_HANDLER  // COMSIG_MOVABLE_MOVED
    do_something()

/datum/component/foo/proc/on_enter(datum/source, atom/enterer)
    SIGNAL_HANDLER  // COMSIG_ATOM_ENTERED + COMSIG_ATOM_INITIALIZED_ON
    do_something_else()

If your proc does have something that needs to sleep (such as a do_after()), do not simply omit the SIGNAL_HANDLER. Instead, call the sleeping code with INVOKE_ASYNC from within the signal handling function.

/atom/movable/proc/when_moved(atom/movable/A)
    SIGNAL_HANDLER  // COMSIG_MOVABLE_MOVED
    INVOKE_ASYNC(src, PROC_REF(thing_that_sleeps), arg1)

Operators

Spacing of operators

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

Use of operators

  • Bitwise ANDs (&) should be written as bitfield & bitflag NEVER bitflag & bitfield. Both are valid, but the latter is confusing and nonstandard.
  • Associated lists declarations must have their key value quoted if it’s a string.
//Bad
list(a = "b")

//Good
list("a" = "b")

Bitflags

Bitshift operators are mandatory, opposed to directly typing out the value:

#define MACRO_ONE (1<<0)
#define MACRO_TWO (1<<1)
#define MACRO_THREE (1<<2)

Is accepted, whereas the following is not:

#define MACRO_ONE 1
#define MACRO_TWO 2
#define MACRO_THREE 4

While it may initially look intimidating, (1<<x) is actually very simple and, as the name implies, shifts the bits of a given binary number over by one digit.

000100 (4, or (1<<2))
<<
001000 (8, or (1<<3))

Using this system makes the code more readable and less prone to error.

Legacy Code

SS13 has a lot of legacy code that’s never been updated. Here are some examples of common legacy trends which are no longer acceptable:

  • To display messages to all mobs that can view user, you should use visible_message().
//Bad
for(var/mob/M in viewers(user))
    M.show_message("<span class='warning'>Arbitrary text</span>")

//Good
user.visible_message("<span class='warning'>Arbitrary text</span>")
  • You should not use color macros (\red, \blue, \green, \black) to color text, instead, you should use span classes. <span class='warning'>Red text</span>, <span class='notice'>Blue text</span>.
//Bad
to_chat(user, "\red Red text \black Black text")

//Good
to_chat(user, "<span class='warning'>Red text</span>Black text")
  • To use variables in strings, you should never use the text() operator, use embedded expressions directly in the string.
//Bad
to_chat(user, text("[] is leaking []!", name, liquid_type))

//Good
to_chat(user, "[name] is leaking [liquid_type]!")
  • To reference a variable/proc on the src object, you should not use src.var/src.proc(). The src. in these cases is implied, so you should just use var/proc().
//Bad
var/user = src.interactor
src.fill_reserves(user)

//Good
var/user = interactor
fill_reserves(user)

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 proper parameters (values starting with a :). You can then replace these with a list of parameters, and these will be properly escaped during the query, and prevent any SQL injection.

//Bad
var/datum/db_query/query_watch = SSdbcore.NewQuery("SELECT reason FROM [format_table_name("watch")] WHERE ckey='[target_ckey]'")

//Good
var/datum/db_query/query_watch = SSdbcore.NewQuery("SELECT reason FROM [format_table_name("watch")] WHERE ckey=:target_ckey", list(
    "target_ckey" = target_ckey
)) // Note the use of parameters on the above line and :target_ckey in the query.

  • 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.

  • 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.

Modular Code in a File

  • 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 (e.g. a new tool would go in the tools.dm file).

  • Our codebase also has support for checking files so that they only contain one specific typepath, including none of its subtypes. This can be done by adding a specific header at the beginning of the file, which the CI will look for when running. An example can be seen below. You can also run this test locally using /tools/ci/restrict_file_types.py

RESTRICT_TYPE(/datum/foo)

/datum/proc/do_thing() // Error: '/datum' proc found in a file restricted to '/datum/foo'

/datum/foo

/datum/foo/do_thing()

/datum/foo/bar // Error: '/datum/foo/bar' type definition found in a file restricted to '/datum/foo'

/datum/foo/bar/do_thing() // Error: '/datum/foo/bar' proc found in a file restricted to '/datum/foo'

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.

  • Use parameters for queries, as mentioned above in Develop Secure Code.

  • Always check your queries for success with if(!query.warn_execute()). By using this standard format, you can ensure the correct log messages are used.

  • Always qdel() your queries after you are done with them. This cleans up the results and helps things run smoother.

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

  • Any time the schema is changed, the SQL_VERSION defines must be incremented, as well as the example config, with an appropriate conversion kit placed in the SQL/updates folder.

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

Dream Maker Quirks/Tricks

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

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) VS for(var/i in 1 to length(list))

The former is faster than the latter, as shown by the following profile results:

Code used for the test:

var/list/numbers_to_use = list()
proc/initialize_shit()
    for(var/i in 1 to 1000000)
        numbers_to_use += rand(1,100000)

proc/old_loop_method()
    for(var/i in numbers_to_use)
        var/numvar = i

proc/new_loop_method()
    for(var/i in 1 to numbers_to_use.len)
        var/numvar = numbers_to_use[i]

istype()-less for loops

A name for a differing syntax for writing for-each style loops in DM. It’s not DM’s standard syntax, hence why this is considered a quirk. Take a look at this:

var/list/bag_of_items = list(sword1, apple, coinpouch, sword2, sword3)
var/obj/item/sword/best_sword
for(var/obj/item/sword/S in bag_of_items)
    if(!best_sword || S.damage > best_sword.damage)
        best_sword = S

The above is a simple proc for checking all swords in a container and returning the one with the highest damage, and it uses DM’s standard syntax for a for-loop by specifying a type in the variable of the for’s header that DM interprets as a type to filter by. It performs this filter using istype() (or some internal-magic similar to istype() - this is BYOND, after all). This is fine in its current state for bag_of_items, but if bag_of_items contained ONLY swords, or only SUBTYPES of swords, then the above is inefficient. For example:

var/list/bag_of_swords = list(sword1, sword2, sword3, sword4)
var/obj/item/sword/best_sword
for(var/obj/item/sword/S in bag_of_swords)
    if(!best_sword || S.damage > best_sword.damage)
        best_sword = S

The above code specifies a type for DM to filter by.

With the previous example that’s perfectly fine, we only want swords, but if the bag only contains swords? Is DM still going to try to filter because we gave it a type to filter by? YES, and here comes the inefficiency. Wherever a list (or other container, such as an atom (in which case you’re technically accessing their special contents list, but that’s irrelevant)) contains datums of the same datatype or subtypes of the datatype you require for your loop’s body, you can circumvent DM’s filtering and automatic istype() checks by writing the loop as such:

var/list/bag_of_swords = list(sword, sword, sword, sword)
var/obj/item/sword/best_sword
for(var/s in bag_of_swords)
    var/obj/item/sword/S = s
    if(!best_sword || S.damage > best_sword.damage)
        best_sword = S

Of course, if the list contains data of a mixed type, then the above optimisation is dangerous, as it will blindly typecast all data in the list as the specified type, even if it isn’t really that type, causing runtime errors (aka your shit won’t work if this happens).

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.

Global Vars

All new global vars must use the defines in code/__DEFINES/_globals.dm. Basic usage is as follows:

To declare a global var:

GLOBAL_VAR(my_global_here)

To access it:

GLOB.my_global_here = X

There are a few other defines that do other things. GLOBAL_REAL shouldn’t be used unless you know exactly what you’re doing. GLOBAL_VAR_INIT allows you to set an initial value on the var, like GLOBAL_VAR_INIT(number_one, 1). GLOBAL_LIST_INIT allows you to define a list global var with an initial value, etc.