This document contains
examples that you can click on to open them.
# Git - Please do the following *before* sending a pull request: - Merge upstream code (if any) back into your own branch - Run formatters/linters - Push as often as possible - Development is done on separate branches, these follow a pattern of `name/feature` (i.e. `loek/dll-so-poc` or `jaro/class2`) - The master branch is considered stable, and should always contain a working/compiling version of the project - TODO: tagging / versions # Code style - Formatting nitty-gritty is handled by clang-format/clang-tidy (run `make format` in the root folder of this repository to format all sources files) -
ASCII only
GoodBad
```cpp // crepe startup message std::string message = "Hello, world!"; ``` ```cpp // crêpe startup message std::string message = "こんにちは世界"; ```
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Class names are always singular
GoodBad
```cpp class Foo {}; ``` ```cpp class Cars {}; ```
- Source files (`.cpp`, `.hpp`) contain the following types of comments: - What is the code supposed to do (optional) - Implementation details (if applicable) - Header files (`.h`) contain the following types of comments: - [Usage documentation](#documentation) (required) - Implementation details (if they affect the header) - Design/data structure decisions (if applicable) -
Comments are placed *above* the line(s) they are explaining
GoodBad
```cpp int add(int a, int b) { // add numbers int out = a + b; return out; } ``` ```cpp int add(int a, int b) { int out = a + b; // add numbers return out; } ```
- Header includes (at the top of files) are split into paragraphs separated by a blank line. The order is: 1. system headers (using `<`brackets`>`) 2. relative headers NOT in the same folder as the current file 3. relative headers in the same folder as the current file > [!NOTE] > When using libraries of which the header include order is important, make > sure to separate the include statements using a blank line (clang-format > may sort include statements, but does not sort across empty lines).
Example
GoodBad
```cpp #include #include #include "api/Sprite.h" #include "util/log.h" #include "SDLContext.h" ``` ```cpp #include #include "SDLContext.h" #include "util/log.h" #include #include "api/Sprite.h" ```
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If there is one, the matching template header (.hpp) is included at the bottom of the regular header (.h)
GoodBad
Foo.h: ```cpp #pragma once template void foo(); #include "Foo.hpp" ``` Foo.hpp: ```cpp #pragma once #include "Foo.h" template void foo() { // ... } ``` Foo.h: ```cpp #pragma once template void foo(); ``` Foo.hpp: ```cpp #pragma once #include "Foo.h" template void foo() { // ... } ```
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using namespace may not be used in header files (.h, .hpp), only in source files (.cpp).
GoodBad
example.h: ```cpp namespace crepe { void foo(); } ``` example.cpp: ```cpp #include "example.h" using namespace crepe; void foo() {} ``` example.h: ```cpp namespace crepe { template T foo(); } ``` example.hpp: ```cpp #include "example.h" using namespace crepe; template T foo(); ```
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Getter and setter functions are appropriately prefixed with get_ and set_.
GoodBad
```cpp class Foo { public: int get_speed() const; void set_speed(int speed); private: int speed; }; ``` ```cpp class Foo { public: int speed() const; void set_speed(int speed); private: int speed; }; ```
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A singleton's instance is always accessed using a getter function that instantiates its own class as a static variable within the getter function scope, instead of storing the instance as a member variable directly.
GoodBad
```cpp class Foo { Foo & get_instance() { static Foo instance; return instance; } }; ``` ```cpp Foo Foo::instance {}; class Foo { static Foo instance; Foo & get_instance() { return Foo::instance; } }; ```
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Member variable default values should be directly defined in the class/struct declaration instead of using the constructor.
GoodBad
```cpp class Foo { int speed = 0; }; ``` ```cpp class Foo { Foo() : speed(0) {} int speed; }; ```
- Use of the `auto` type is *not* allowed, with the following exceptions: -
When naming the item type in a range-based for loop ```cpp for (auto & item : foo()) { // ... } ```
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When calling template factory methods that explicitly name the return type in the function call signature ```cpp auto ptr = make_unique(); ```
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When fetching a singleton instance ```cpp auto & mgr = crepe::api::Config::get_instance(); ```
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Only use member initializer lists for non-trivial types.
GoodBad
```cpp class Foo { public: Foo() : bar("baz") {} private: std::string bar; }; ``` ```cpp class Foo { public: Foo() : bar(0) {} private: int bar; }; ```
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C++-style structs should define default values for all non-trivial fields.
GoodBad
```cpp struct Foo { int bar = 0; std::string baz; }; ``` ```cpp struct Foo { int bar; std::string baz; }; ```
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Declare incomplete classes instead of including the relevant header where possible (i.e. if you only need a reference or raw pointer).
GoodBad
```cpp class Bar; class Foo { Bar & bar; }; ``` ```cpp #include "Bar.h" class Foo { Bar & bar; }; ```
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Template functions are only declared in a .h header, and defined in a matching .hpp header.
GoodBad
add.h: ```cpp template T add(T a, T b); #include "add.hpp" ``` add.hpp: ```cpp #include "add.h" template T add(T a, T b) { return a + b; } ``` add.h: ```cpp template T add(T a, T b) { return a + b; } ```
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Where possible, end (initializer) lists with a trailing comma (e.g. with structs, enums)
GoodBad
```cpp enum Color { Red, Green, Blue, }; ``` ```cpp enum Color { Red, Green, Blue }; ```
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#pragma should be used instead of include guards
GoodBad
```cpp #pragma once // ... ``` ```cpp #ifndef __INCLUDED_H #define __INCLUDED_H // ... #endif ```
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Variables that are being moved always use the fully qualified std::move
GoodBad
```cpp using namespace std; string foo = "bar"; ref_fn(std::move(foo)); ``` ```cpp using namespace std; string foo = "bar"; ref_fn(move(foo)); ```
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If possible, classes and structs are passed to functions by (const) reference
GoodBad
```cpp void foo(const Point & p); ``` ```cpp void foo(Point & p); void bar(Point p); ```
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Follow the rule of five
GoodBad
```cpp class Foo { public: Foo(); ~Foo(); Foo(Foo &&) noexcept; Foo & operator = (const Foo &); Foo & operator = (Foo &&) noexcept; }; ``` ```cpp class Foo { public: Foo(); ~Foo(); }; ```
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Ensure const-correctness
GoodBad
```cpp class Foo { public: int get_value() const; void set_value(int new_value); const std::string & get_name() const; void set_name(const std::string & new_name); private: int value; std::string name; }; ``` ```cpp class Foo { public: int get_value(); void set_value(int new_value); std::string get_name(); void set_name(std::string new_name); private: int value; std::string name; }; ```
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Files should be named after the class/struct/interface they implement
GoodBad
```cpp MyClass.h MyClass.cpp MyClass.hpp ``` ```cpp my_class.h myClass.cpp my-class.hpp ```
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Implementations are not allowed in header files, except if the implementation - is `= default` - is `= delete` - is `{}` (empty) - only returns a constant literal
GoodBad
```cpp class Foo { public: int get_value() const { return 42; } }; ``` ```cpp class Foo { public: int calculate_value() const { int result = 0; // complex calculation return result; } }; ```
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Use angle brackets (<>) only for including system headers and double quotes ("") for including other engine files. > [!NOTE] > Only files in the examples folder should include engine headers with angle > brackets
GoodBad
```cpp #include #include "facade/Sound.h" ``` ```cpp #include #include ```
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Ensure exception safety by using RAII classes
GoodBad
```cpp auto foo = std::make_unique(); ``` ```cpp Foo* foo = new Foo(); // ... delete foo; ```
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Do not use C-style memory management APIs (malloc, calloc, free)
GoodBad
```cpp Foo * foo = new Foo(); delete foo; ``` ```cpp Foo * foo = (Foo *) malloc(sizeof(Foo)); free(foo); ```
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Prefix all class members with this->
GoodBad
```cpp void Foo::set_value(int value) { this->value = value; } ``` ```cpp void Foo::set_value(int new_value) { value = new_value; } ```
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Assigning booleans should be done with the true/false literals instead of 0/1
GoodBad
```cpp bool foo = true; bool bar = false; ``` ```cpp bool foo = 1; bool bar = 0; ```
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The reason for friend relations are documented
GoodBad
```cpp //! ComponentManager calls the private constructor of this class friend class ComponentManager; ``` ```cpp friend class ComponentManager; ```
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Do not pick fixed-width integer types (unless required)
GoodBad
```cpp unsigned long long foo(); ``` ```cpp uint64_t foo(); ```
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Throw exceptions using standard C++ exceptions (such as std::runtime_error)
GoodBad
```cpp if (error) { throw std::runtime_error("An error occurred"); } ``` ```cpp if (error) { throw "An error occurred"; } ```
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Constructors of classes derived from Component should be protected and ComponentManager should be declared as a friend class.
GoodBad
```cpp class MyComponent : public Component { protected: MyComponent() = default; friend class ComponentManager; }; ``` ```cpp class MyComponent : public Component { public: MyComponent() = default; }; ```
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Use of format specifiers (like %s and %n) are not allowed (use {} with std::format instead)
GoodBad
```cpp std::string message = std::format("Hello, {}", name); ``` ```cpp char message[50]; sprintf(message, "Hello, %s", name); ```
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Argument names should be added in .h files (not only in .cpp and .hpp files)
GoodBad
Foo.h: ```cpp void foo(int bar); ``` Foo.cpp: ```cpp void foo(int bar) { // ... } ``` Foo.h: ```cpp void foo(int); ``` Foo.cpp: ```cpp void foo(int bar) { // ... } ```
## CMakeLists-specific - Make sure list arguments (e.g. sources, libraries) given to commands (e.g. `target_sources`, `target_link_libraries`) are on separate lines. This makes resolving merge conflicts when multiple sources were added by different people to the same CMakeLists.txt easier. # Structure - Files are placed in the appropriate directory: |Path|Purpose| |-|-| |`crepe/`|Auxiliary, managers| |`crepe/api/`|User-facing APIs| |`crepe/util/`|Standalone utilities and helper functions| |`crepe/system/`|(ECS) system classes| |`crepe/facade/`|Library façades| - Do not (indirectly) include private *dependency* headers in API header files, as these are no longer accessible when the engine is installed - All code is implemented under the `crepe` namespace. - Header files declare either a single class or symbols within a single namespace. # Documentation - All documentation is written in U.S. English -
Doxygen commands are used with a backslash instead of an at-sign.
GoodBad
```cpp /** * \brief do something * * \param bar Magic number */ void foo(int bar); ``` ```cpp /** * @brief do something * * @param bar Magic number */ void foo(); ```
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The default constructor and destructor aren't required to have a \brief description
GoodBad
```cpp Foo(); virtual ~Foo(); ``` ```cpp //! Create instance of Foo Foo(); //! Destroy instance of Foo virtual ~Foo(); ```
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Parameter direction shouldn't be specified using Doxygen
GoodBad
```cpp /** * \param bar Reference to Bar */ void foo(const Bar & bar); ``` ```cpp /** * \param[in] bar Reference to Bar */ void foo(const Bar & bar); ```
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Deleted functions shouldn't have Doxygen comments
GoodBad
```cpp // singleton Foo(const Foo &) = delete; Foo(Foo &&) = delete; Foo & operator=(const Foo &) = delete; Foo & operator=(Foo &&) = delete; ``` ```cpp //! Deleted copy constructor Foo(const Foo &) = delete; //! Deleted move constructor Foo(Foo &&) = delete; //! Deleted copy assignment operator Foo & operator=(const Foo &) = delete; //! Deleted move assignment operator Foo & operator=(Foo &&) = delete; ```
# Libraries - External libraries should be included as Git submodules under the `lib/` subdirectory - When adding new submodules, please set the `shallow` option to `true` in the [.gitmodules](./.gitmodules) file