Standardize implementation guidelines in the wiki: get methods.

[IAmNotHanni]

We already talked about how to implement get methods consistently:

Rules

• Name: Don't use prefix get_. Give the get method the same name as the resource it returns.
• For complex types (std::vector, std::string), return a const reference.
• Don't const the return type for simple types (int, float), because this prevents move semantics to be applied.
• For simple types (int, float), just copy the return value.
• Mark get methods as [[nodiscard]] in the header file only.
• Mark get methods as const, so they don't change members.
• Do not add documentation for get methods, since it is self-explanatory.
• Keep get methods directly in the header file.
• Do not add inline since get methods in header files are always inlined.
• The get method should not run any other code, like checking if the value is actually valid. Since we are using RAII, the value to return must be in a valid state anyways.
• Use operator overloading sparingly.

Examples

[[nodiscard]] const glm::vec3& position() const {
    return m_position;
}

[[nodiscard]] float aspect_ratio() const {
    return m_aspect_ratio;
}

[IceflowRE]

• Add a note in the contributing guide to read the development section carefully.

[IAmNotHanni]

#222

[IceflowRE]

Also the documentation which is affacted is here https://github.com/inexorgame/vulkan-renderer/tree/master/documentation/source/development/engine-design

[IAmNotHanni]

cpp-best-practices/cppbestpractices#21