New coding guidelines

This page contains current coding guidelines.

Code styling

Please stick to these rules to write nice and good code!

Avoid magic numbers

We always try to avoid magic numbers like memory addresses, offsets, some constant numbers, etc. You can use the #define macro to define the numbers or at least use comments to document these numbers.

float CWeatherSA::GetWetRoads() const
{
    return *(float*)0xC81308; // CWeather::WetRoads
}

// In the header
#define NUM_WETROADS    0xC81308

// In the .cpp
float CWeatherSA::GetWetRoads() const
{
    return *(float*)NUM_WETROADS;
}

When using the #define macro, we use a prefix that specifies what it defines.

#define FUNC_RemoveRef                               0x4C4BB0 // Function address
#define ARRAY_aCannons                               0xC80740 // Array address
#define STRUCT_CAESoundManager                       0xB62CB0 // Struct address
#define SIZE_CWaterCannon                            0x3CC    // Size of object (e.g., struct object)
#define CLASSSIZE_WeaponInfo                         112      // Class size
#define NUM_CWaterCannon_Audio_Offset                0x32C    // Number (e.g., offsets, integers, etc.)
#define CLASS_CText                                  0xC1B340 // Class address
#define VAR_CTempColModels_ModelPed1                 0x968DF0 // Variable address (CColModel colModelPeds)

Naming conventions

We use different naming conventions depending on the context.

• Use lower camel case for variable names and types:

  SSomeStruct   valueOne;
  ESomeEnum     m_valueTwo;
  

• Use upper camel case for functions and classes:

  void UpperCamelCase();
  class Vector;
  

• Class member, should start with the prefix m_

  CVector       m_vecPosition;
  CVector       m_vecRotation;
  bool          m_isVisible;
  bool          m_isFrozen;
  

• We avoid Hungarian notation in new codes, so use it only if necessary for consistency with the current code you are editing.

  float         fValue;               // Local variable
  unsigned char m_ucValue;            // Class member variable
  char          ms_cValue;            // Class static member variable
  bool          g_bCrashTwiceAnHour;  // Global variable
  char*         szUsername;           // Zero-terminated string
  SString       strUsername;          // String
  CVector       vecPosition;          // 3D Vector
  

Functions without arguments

Define and call functions without arguments simply with empty parentheses. Don't use void in this case as it is an old practice!

// Bad
void MyFunction(void);
MyFunction(void);

// Good
void MyFunction();
MyFunction();

Code readability

This is another very important point of the guidelines. Always try to make your code as readable as possible so that anyone can easily read it and understand its purpose.

• Use early-returns to improve code readability.

  // Poor readability
  bool CStaticFunctionDefinitions::RespawnObject(CElement* pElement)
  {
      if (IS_OBJECT(pElement))
      {
          CObject* pObject = static_cast<CObject*>(pElement);
          if (pObject)
          {
              pObject->Respawn();
              return true;
          }
      }
  
      return false;
  }
  
  // Clearer readability
  bool CStaticFunctionDefinitions::RespawnObject(CElement* pElement)
  {
      if (!IS_OBJECT(pElement))
          return false;
  
      CObject* pObject = static_cast<CObject*>(pElement);
      if (!pObject)
          return false;
  
      pObject->Respawn();
  
      return true;
  }
  
  

• Always strive to maintain code readability. If a type is lengthy to write, you can use auto to improve readability

  CDeatchmatchObject* pObject = static_cast<CDeathmatchObject*>(pEntity);
  // Can be
  auto* pObject = static_cast<CDeathmatchObject*>(pEntity);
  

  We prefer to use auto* when it comes to pointer, even though auto itself is sufficient.

• Use logical conditions whenever possible

  // Poor readability
  const CPositionRotationAnimation* CObject::GetMoveAnimation()
  {
      if (IsMoving())
      {
          return m_pMoveAnimation;
      }
      else
      {
          return nullptr;
      }
  }
  
  // Good readability
  const CPositionRotationAnimation* CObject::GetMoveAnimation()
  {
      return IsMoving() ? m_pMoveAnimation : nullptr;
  }
  

• if a loop or condition is short, omit curly braces

  // Instead of
  if (!bStillRunning)
  {
      StopMoving();
  }
  
  // You can do
  
  if (!bStillRunning)
      StopMoving();
  
  // However, do not omit curly braces for larger blocks:
  <syntaxhighlight lang="cpp">
  for (dont)
      for (do)
          for (this)
              ...
  

• Functions that only return a value should be placed in header files. For example, instead of:

  // In .cpp file
  int GetGameSpeed()
  {
      return m_iGameSpeed;
  }
  

  Do it in the header:

  int GetGameSpeed() const noexcept { return m_iGameSpeed; }
  

• Don't use unnecessary parenthesis.

  // Bad
  bool CClientPed::IsDead()
  {
      (return (m_status == STATUS_DEAD));
  }
  
  // Good
  bool CClientPed::IsDead()
  {
      return m_status == STATUS_DEAD;
  }
  

• Use range-based for loops when possible.

  std::vector<int> vec; // Example std container
  
  // Bad:
  for (std::vector<int>::iterator it = vec.begin(); it != vec.end(); it++)
  
  // Good:
  for (const auto& v : vec)
  for (const int& v : vec)
  
  // In case of maps you can use structured binding:
  std::map<std::string, int> myMap;
  for (const auto& [k, v] : myMap)
  
  // There are situations where you must use old style loops, in this case use `auto`
  for (auto it = vec.begin(); it != vec.end(); it++)
  

Coding conventions

We always try to create good code that complies with applicable conventions.

Specifiers

These are the basic specifiers we try to use, especially in new codes:

• Use const and constexpr wherever possible.
• Use the noexcept specifier whenever possible, but be cautious as it can cause the program to terminate if an exception is thrown.

Null pointers

Use nullptr instead of NULL when setting or returning a null pointer.

Initializing a class member

Use member initialization lists whenever possible. Instead of doing:

CObject::CObject(CElement* pParent, CObjectManager* pObjectManager, bool bIsLowLod) 
    : CElement(pParent), m_bIsLowLod(bIsLowLod), m_pLowLodObject(NULL)
{
    // Init
    m_iType = CElement::OBJECT;
    SetTypeName("object");

    m_pObjectManager = pObjectManager;
    m_usModel = 0xFFFF;
    m_pMoveAnimation = NULL;
    m_ucAlpha = 255;
    m_vecScale = CVector(1.0f, 1.0f, 1.0f);
    m_fHealth = 1000.0f;
    m_bSyncable = true;
    m_pSyncer = NULL;
    m_bIsFrozen = false;
    m_bDoubleSided = false;
    m_bBreakable = false;
    m_bCollisionsEnabled = true;

    // Add us to the manager's list
    pObjectManager->AddToList(this);
}

Do:

CObject::CObject(CElement* pParent, CObjectManager* pObjectManager, bool bIsLowLod)
    : CElement(pParent),
      m_bIsLowLod(bIsLowLod),
      m_pLowLodObject(nullptr),
      m_iType(CElement::OBJECT),
      m_pObjectManager(pObjectManager),
      m_usModel(0xFFFF),
      m_pMoveAnimation(nullptr),
      m_ucAlpha(255),
      m_vecScale(1.0f, 1.0f, 1.0f),
      m_fHealth(1000.0f),
      m_bSyncable(true),
      m_pSyncer(nullptr),
      m_bIsFrozen(false),
      m_bDoubleSided(false),
      m_bBreakable(false),
      m_bCollisionsEnabled(true)
{
    SetTypeName("object");

    // Add us to the manager's list
    pObjectManager->AddToList(this);
}

Typing conventions

1. In C++, prefer using types from the std namespace provided by appropriate headers (such as <cstdint>, <cstddef>, etc.). This is recommended for several reasons:
   • Namespace Safety: Types defined in these headers are encapsulated within the std namespace, which helps avoid naming conflicts with user-defined types or macros. This follows the C++ standard practice of minimizing global namespace pollution.
   • Consistency and Readability: Using std:: types ensures consistency and improves code readability by making it clear that these types are part of the standard library.
   • C++ Standard Compliance: The C++ standard (C++11 and later) includes headers like <cstdint> and <cstddef>, which provide standardized types:

   • <cstdint> includes exact-width integer types such as 'std::uint32_t, std::int32_t, etc.
   • <cstddef> includes types like std::size_t, std::ptrdiff_t, etc.

   • Portability and Maintainability: Using these headers makes your code more portable across different compilers and platforms, as it guarantees that these types are defined in a standardized way. This is especially important in a C++ environment, where the focus is on maintainability and cross-platform compatibility.
   By adhering to these practices, you ensure that your codebase remains clean, consistent, and adheres to modern C++ standards, which ultimately contributes to better maintainability and fewer integration issues.
2. In new codes, try not to use the SString type anymore, use std::string instead.

Header files

• Always place a copyight comment at the beginning of header files

  /*****************************************************************************
  \
  *
  *  PROJECT:     Multi Theft Auto
  *  LICENSE:     See LICENSE in the top level directory
  *  FILE:        Client/mods/deathmatch/logic/CClientIFP.h
  *  PURPOSE:     Animations replacement
  *
  *  Multi Theft Auto is available from https://www.multitheftauto.com/
  *
  *****************************************************************************/
  
  #pragma once
  

  The FILE field contains the path of the current header file.

• Put #pragma once preprocessor directive next to the copyright comment for new header files and the ones you are modifying for the pull request. Make sure to remove include guard if you are using #pragma once.