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Code Conventions

When contributing, you must follow our code conventions. Otherwise, CI builds will automatically fail and your PR will not be merged until the non-conforming code is fixed. Due to this, we strongly advise you to run src/CheckBasicStyle.lua before committing, it will perform various code style checks and warn you if your code does not conform to our conventions. CheckBasicStyle.lua can be configured to run automatically before every commit via a pre-commit hook, this is highly recommended. There are instructions on how to achieve this at the bottom of this file.

Here are the conventions:

  • We use the subset of C++11 supported by MSVC 2013 (ask if you think that something outside of this subset would be useful)
  • All new public functions in all classes need documenting comments on what they do and what behavior they follow, use doxy-comments formatted as /** Description */. Do not use asterisks on additional lines in multi-line comments.
  • Use spaces after the comment markers: // Comment instead of //Comment. A comment must be prefixed with two spaces if it's on the same line with code:
  • SomeFunction()<Space><Space>//<Space>Note the two spaces prefixed to me and the space after the slashes.
  • All variable names and function names use CamelCase style, with the exception of single letter variables.
  • ThisIsAProperFunction() This_is_bad() this_is_bad() GoodVariableName badVariableName.
  • All member variables start with m_, all function parameters start with a_, all class names start with c.
  • class cMonster { int m_Health; int DecreaseHealth(int a_Amount); }
  • Put spaces after commas. Vector3d(1, 2, 3) instead of Vector3d(1,2,3)
  • Put spaces before and after every operator.
  • a = b + c;
  • if (a == b)
  • Keep individual functions spaced out by 5 empty lines, this enhances readability and makes navigation in the source file easier.
  • Add those extra parentheses to conditions, especially in C++:
  • if ((a == 1) && ((b == 2) || (c == 3))) instead of ambiguous if (a == 1 && b == 2 || c == 3)
  • This helps prevent mistakes such as if (a & 1 == 0)
  • Use the provided wrappers for OS stuff:
  • Threading is done by inheriting from cIsThread, thread synchronization through cCriticalSection and cEvent, file access and filesystem operations through the cFile class, high-precision timers through cTimer, high-precision sleep through cSleep
  • No magic numbers, use named constants:
  • E_ITEM_XXX, E_BLOCK_XXX and E_META_XXX for items and blocks
  • cEntity::etXXX for entity types, cMonster::mtXXX for mob types
  • dimNether, dimOverworld and dimEnd for world dimension
  • gmSurvival, gmCreative, gmAdventure for game modes
  • wSunny, wRain, wThunderstorm for weather
  • cChunkDef::Width, cChunkDef::Height for chunk dimensions (C++)
  • etc.
  • Instead of checking for a specific value, use an IsXXX function, if available:
  • cPlayer:IsGameModeCreative() instead of (cPlayer:GetGameMode() == gmCreative) (the player can also inherit the gamemode from the world, which the value-d condition doesn't catch)
  • Please use tabs for indentation and spaces for alignment. This means that if it's at line start, it's a tab; if it's in the middle of a line, it's a space
  • Alpha-sort stuff that makes sense alpha-sorting - long lists of similar items etc.
  • White space is free, so use it freely
  • "freely" as in "plentifully", not "arbitrarily"
  • All case statements inside a switch need an extra indent
  • Each and every control statement deserves its braces. This helps maintainability later on when the file is edited, lines added or removed - the control logic doesn't break so easily
  • The only exception: a switch statement with all case statements being a single short statement is allowed to use the short brace-less form
  • These two rules really mean that indent is governed by braces
  • Add an empty last line in all source files (GCC and Git can complain otherwise)

Pre-commit hook

When contributing, the code conventions above must be followed. Otherwise, the CI builds will automatically fail and your PR will not be merged until the non-conforming code is fixed. It is highly recommended to set up a pre-commit hook which will check your code style before every commit. Here is how to do that:

  • Clone the repository as usual.
  • Go to your <clone location>/.git/hooks folder, create a text file named "pre-commit" there with the following contents:
src/CheckBasicStyle.lua 1>&2 -g
  • If on Linux/Unix, you need to give the newly created file an execute permission: chmod +x .git/hooks/pre-commit
  • Lua must be installed.
  • You're done. Now, src/CheckBasicStyle.lua will check the changed files before every commit. If a problem is found, it will point you to that problem and will cancel the commit.

Note that the check script is not smart enough to catch everything, so not having any warnings does not necessarily imply that you followed the conventions fully. The other humans working on this will perform more checks before merging.

Your must either place your work in the public domain or licensed it under the Apache License 2.0, and if so you must add yourself to the contributors file to show that you accept the publication of your work under the license.

PLUGINS ONLY: If your plugin is not licensed under the Apache license, then it must be compatible and marked as such. This is only valid for the plugins included within the Cuberite source; plugins developed on separate repositories can use whatever license they want.