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Style Guide

This is the style you must follow when writing code. It's important to note that large parts of the codebase do not consistently follow these rules, but this does not free you of the requirement to follow them.

  1. General Guidelines
  2. Paths and Inheritence
  3. Variables
  4. Procs
  5. Things that do not matter

General Guidelines

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"

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))

Operators

Spacing

  • 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")

Use static instead of global

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.

Use early returns

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.

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!

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()

Paths and Inheritence

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

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.

Variables

Use var/name format when declaring variables

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

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)

Procs

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

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.

Prefer named arguments when the meaning is not obvious.

Pop-quiz, what does this do?

give_pizza(TRUE, 2)

Well, obviously the TRUE makes the pizza hot, and 2 is the number of toppings.

Code like this can be very difficult to read, especially since our LSP does not show argument names at this time. Because of this, you should prefer to use named arguments where the meaning is not otherwise obvious.

give_pizza(hot = TRUE, toppings = 2)

What is "obvious" is subjective--for instance, give_pizza(PIZZA_HOT, toppings = 2) is completely acceptable.

Other examples:

deal_damage(10) // Fine! The proc name makes it obvious `10` is the damage...at least it better be.
deal_damage(10, FIRE) // Also fine! `FIRE` makes it obvious the second parameter is damage type.
deal_damage(damage = 10) // Redundant, but not prohibited.

use_power(30) // Fine! `30` is obviously something like watts.
turn_on(30) // Not fine!
turn_on(power_usage = 30) // Fine!

set_invincible(FALSE) // Fine! Boolean parameters don't always need to be named. In this case, it is obvious what it means.

Things that do not matter

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!