yarn/CONVENTIONS.md

Naming conventions

General

Use UpperCamelCase for class names. Use lowerCamelCase for method names, variable names, and names of fields that are not both static and final. Use UPPER_SNAKE_CASE for names of fields that are both static and final.

Method names should generally be verb phrases (tick, getCarversForStep), except for "withX", "toX", "fromX", "of" and builder methods. Class names and non-boolean field and variable names should be noun phrases (ChunkRegion, color). Boolean field and variable names should always be adjective phrases or present tense verb phrases (powered, canOpen), avoiding the is and has prefixes when possible (colored, not isColored or hasColor).

To make code as easy to read as possible, keep names in the natural language order. For example, a class representing a chest block entity should be named ChestBlockEntity rather than BlockEntityChest. Though prefix naming may be helpful for grouping classes together in an IDE's tree view, reading and writing code is done much more often than browsing files.

Spelling

Use American English for consistency throughout Yarn and with known Mojang names.

If there are two accepted spellings of the same word, first check if one is already being used in Yarn or by Mojang, and if not, use the most common spelling.

Conciseness

Omit words that are made redundant by parameter names or owner class names. For example, use getChunk(BlockPos pos) rather than getChunkAtPosition(BlockPos pos) and Box.create rather than Box.createBox. Don't avoid overloading methods or shadowing fields.

However, it's more important for a name to be descriptive rather than short, so don't omit important words. When naming something always look at all its usages, including overriding methods and inheriting classes.

It's important to be concise especially with names used in many places throughout the code, while more obscure names can be longer and more descriptive.

Abbreviations

Avoid abbreviations unless it's a common one everyone knows and other yarn names involving the same word use its abbreviated form. Full names are easier to read quickly and remember ("Which words were abbreviated?") and they often don't take more time to type thanks to IDE autocompletion. Common abbreviations you should use are:

• "id" for "identifier"
• "pos" for "position"
• "nbt" for "named binary tag"
• "init" for "initialize"
• Any abbreviations used by Java or libraries ("json", "html", etc.)

Treat acronyms as single words rather than capitalising every letter. This improves readability (compare JsonObject and JSONObject) and it's consistent with Mojang naming (a known name is NbtIo).

Packages

Package names should always be singular to respect Java conventions. Try to respect the Mojang package structure to avoid visibility problems in the future.

Consistency

Consistency is important as it makes code more readable and names easier to memorize. When possible, use terms that are present in other Yarn names, in libraries used by Minecraft, or in vanilla strings. The rest of this section lists common names and name patterns you should use.

Ticks and updates

Use "tick" for updates done once per tick. Use "update" for other kind of updates.

Value last tick

Use the word "last" for the value that something had last tick (lastX, lastWidth, etc.).

Getters, setters, withers, and creators

Use "get" for non-boolean getters and other methods that calculate some property with no side effects other than caching a value in a private field. For boolean getters, use "is".

Use "set" for methods that set some property. Name the parameter the same as the property (setColor(color), not setColor(newColor)).

Use "with" for methods that return a copy of an object with a different value for some property. Name the parameter the same as the property.

Use "create" for methods that create a new instance of some object. Use "get or create" for methods that create a new instance only if one does not already exist. Don't use "get or create" for lazy initialization, though.

Serialization

Use "serializer" for objects whose purpose is serializing or deserializing some type of object (RecipeSerializer). Use "serialize" and "deserialize" for methods only when serializing or deserializing an object other than the one the method is in.

Use "from" for static methods that create an object of the method owner's type (fromJson, fromNbt, fromString). Use "to" for methods that convert an object to another type (toString, toLong, toNbt).

Use "read" for non-static methods that load data into the object. Use "write" for methods that save data to an existing object passed as a parameter.

Factories and builders

Use "factory" for objects whose purpose is creating other objects.

Use "builder" for objects whose purpose is helping with the creation of an immutable object. Name builder methods the same as the field they're setting, without any prefix.

Collections

Use a plural name for collections and maps rather than the words "list", "set", "array", etc., unless it's a collection of collections or there are several collections of different types containing the same objects (entities, entityLists).

When it's enough, name maps based on the value type. Otherwise, name it in the "valuesByKeys" format.

Coordinates

Coordinates can be named x, y, and z when it's clear what they represent. If clarification is needed, add a word in front of the coordinate (velocityX, not xVelocity).

Name screen coordinates x and y, rather than left and top.

Mojang names

Do not use names from Mojang's obfuscation maps.

Use names that match names in strings in the vanilla code, unless that string is outdated or inaccurate. This avoids confusion, especially from new modders who may not understand what an class exception message is referring to.

Even if a known Mojang name doesn't appear in any strings, it's a good idea to use it since the official name is a good indicator of the the class's actual purpose and makes it less likely the name will have to be changed in the future. For example, don't name a class that Mojang calls BedrockBlock NoSpawningBlock, even if its only purpose is to disable mob spawning, because Mojang may decide to override more methods in that class, breaking mods that were using it in an unexpected way.

There are however three exceptions to this rule:

• Use "world" for what Mojang calls "level" (see https://github.com/FabricMC/yarn/issues/89)
• Use "screen handler" or "handler" (depending on context; if the screen part is obvious it can be omitted) for what Mojang calls "menu" (see https://github.com/FabricMC/yarn/pull/1106)
• Use "inventory" for what Mojang calls "container" (no issue yet)

Things to avoid

Don't name methods based on implementation details. Names should describe what methods do, not how they work.

Avoid including Java-related information in names. For example, don't prefix class names with I, or Enum and don't prefix methods with private. Instead, try to find meaningful names to describe differences between classes. In the case of abstract classes, this may involve renaming subclasses to more specific names.