Code Style Guide - Minecraft Community Edition

Overview

This guide outlines the coding standards and conventions used in Minecraft Community Edition. Consistency is important for maintainability and collaboration.

General Principles

Readability: Code should be clear and self-documenting
Consistency: Follow existing patterns in the codebase
Maintainability: Write code that others can understand and modify
Performance: Consider performance implications, especially in hot paths

Naming Conventions

Classes and Structs

Class names use PascalCase:

class Entity { };
class TileEntity { };
class MinecraftServer { };

Member Variables

Member variables use camelCase:

class Tile {
    int lightEmission;
    float destroyTime;
    bool isTransparent;
};

Static Members

Static members follow the same camelCase convention:

static Tile *rock;
static wstring TILE_DESCRIPTION_PREFIX;
static const float INDESTRUCTIBLE_DESTROY_TIME = -1.0f;

Constants

Constants use UPPER_SNAKE_CASE:

static const int TILE_NUM_COUNT = 4096;
static const int TILE_NUM_MASK = 0xfff;
static const int TILE_NUM_SHIFT = 12;

Methods and Functions

Method names use camelCase:

void updateEntity();
int getSmallId();
void setPosition(float x, float y, float z);

Namespaces

The project uses Java-style namespace organization through header file naming:

#include "net.minecraft.world.entity.h"
#include "net.minecraft.world.level.tile.h"
#include "net.minecraft.world.item.h"

File Organization

Header Files

Header files follow this structure:

#pragma once

// System includes
#include <string>
#include <vector>

// Project includes
#include "Material.h"
#include "Vec3.h"

using namespace std;

// Forward declarations
class Level;
class Player;

// Class definition
class Tile {
public:
    // Public members
protected:
    // Protected members
private:
    // Private members
};

Source Files

Source files follow this structure:

#include "stdafx.h"

// Related header files
#include "net.minecraft.world.h"
#include "net.minecraft.world.entity.h"

// Local header
#include "Entity.h"

// Static member initialization
int Entity::entityCounter = 2048;

// Implementation
void Entity::update() {
    // ...
}

Always include stdafx.h first in .cpp files for precompiled header support.

Code Formatting

Indentation

Use tabs (not spaces)
Tab width: 4 characters
Indent each level consistently

Braces

Use K&R style bracing (opening brace on same line):

if (condition) {
    // code
} else {
    // code
}

for (int i = 0; i < count; i++) {
    // code
}

class MyClass {
public:
    void myMethod() {
        // code
    }
};

Spacing

Space after keywords: if (condition), for (int i = 0; ...)
No space between function name and parentheses: doSomething()
Space around operators: a + b, x = y, i < count

Line Length

No strict limit, but prefer keeping lines reasonably short
Break long lines logically for readability

Comments and Documentation

Code Comments

Use comments to explain why, not what:

// 4J - changed initialiser to 2048, as we are using range 0 - 2047 
// as special unique smaller ids for things that need network tracked
int Entity::entityCounter = 2048;

// If we are the server, check if there are any small Ids which are
// still in the ServerPlayer's vectors of entities to be removed
if (TlsGetValue(tlsIdx) != 0) {
    // ...
}

Team Comments

The codebase includes developer/team tags:

// 4J added so we can have separate shapes for different threads
class ThreadStorage { };

// 4J Stu - Stair tile accesses the protected members
friend class StairTile;

When making significant changes, consider adding your own tags to track modifications.

TODO Comments

Use TODO comments for future work:

// TODO: Optimize this loop for better performance
// TODO: Add validation for negative values

C++ Standards

Pointers and References

Use pointers (*) for optional/nullable values
Use references (&) for required parameters
Prefer smart pointers where appropriate

void processEntity(Entity* entity);  // May be null
void updateLevel(Level& level);      // Required, not null

Memory Management

Be explicit about ownership
Clean up resources properly
Use RAII patterns where appropriate
Be careful with manual new/delete

Type Usage

Use int for general integers
Use unsigned int for bit flags and sizes
Use float for game coordinates and math
Use wstring for text (wide strings)
Use bool for boolean values

Platform-Specific Code

When adding platform-specific code:

#ifdef PLATFORM_DURANGO
    // Xbox-specific code
#endif

#ifdef PLATFORM_WINDOWS
    // Windows-specific code
#endif

Best Practices

Avoid Magic Numbers

Use named constants:

// Bad
if (value > 4096) { }

// Good
static const int MAX_TILES = 4096;
if (value > MAX_TILES) { }

Prefer Early Returns

// Prefer this
if (!isValid) {
    return;
}
// Continue with main logic

// Over deeply nested code
if (isValid) {
    // lots of nested code
}

Initialization

Initialize variables when declaring them:

int count = 0;
Entity* entity = nullptr;
bool isActive = false;

Code Review Checklist

Before submitting code:

Follows naming conventions
Properly formatted (tabs, bracing, spacing)
Comments explain complex logic
No compiler warnings
Builds without errors
Consistent with surrounding code

Learning from the Codebase

The best way to understand the code style is to read existing code:

Minecraft.World/Tile.cpp - Good example of static initialization
Minecraft.World/Entity.cpp - Complex entity management patterns
Header files in net.minecraft.world.*.h - Project organization

When in doubt, look at how similar code is written elsewhere in the project and follow that pattern.

​Overview

​General Principles

​Naming Conventions

​Classes and Structs

​Member Variables

​Static Members

​Constants

​Methods and Functions

​Namespaces

​File Organization

​Header Files

​Source Files

​Code Formatting

​Indentation

​Braces

​Spacing

​Line Length

​Comments and Documentation

​Code Comments

​Team Comments

​TODO Comments

​C++ Standards

​Pointers and References

​Memory Management

​Type Usage

​Platform-Specific Code

​Best Practices

​Avoid Magic Numbers

​Prefer Early Returns

​Initialization

​Code Review Checklist

​Learning from the Codebase

Overview

General Principles

Naming Conventions

Classes and Structs

Member Variables

Static Members

Constants

Methods and Functions

Namespaces

File Organization

Header Files

Source Files

Code Formatting

Indentation

Braces

Spacing

Line Length

Comments and Documentation

Code Comments

Team Comments

TODO Comments

C++ Standards

Pointers and References

Memory Management

Type Usage

Platform-Specific Code

Best Practices

Avoid Magic Numbers

Prefer Early Returns

Initialization

Code Review Checklist

Learning from the Codebase