Header and Includes guidelines

[mgradwohl]

ModernLife will use pre-compiled headers via pch.cpp and pch.h.

Each file should include what it uses, and nothing else: https://github.com/include-what-you-use/include-what-you-use/blob/master/docs/WhyIWYU.md. This means that when a header is added to pch.h it should NOT be removed from the .cpp or .h file that needs it. This makes dependencies of a class unclear and can break refactoring and reuse. If someone wants to use a class you wrote their project (that has a different pch.h, or doesn't use PCH), you have caused them pain.

Header files will use #prgama once as a header guard.

Guidelines for headers and includes are:
Cpp file only:

1. Include pch.h first (do not include pch.h in header files)
2. Headers for the class you are defining (in double quotes) are next.
   Cpp and H files:
3. Standard library headers (in angle brackets).
4. Traditional Windows SDK headers (eg: Windows.h)
5. C++/WinRT projected namespace headers
6. Third-party library headers (e.g. gsl)
7. Any other project-local header (e.g. other classes the project defines and uses)

Example CPP

#include "pch.h"

// these are only for the generated files from WinRT
#include "MainWindow.xaml.h"
#if __has_include("MainWindow.g.cpp")
#include "MainWindow.g.cpp"
#endif

#include <string>
#include <algorithm>

#include <WinUser.h>

#include <winrt/Windows.Foundation.h>
...
#include <winrt/Microsoft.Graphics.Canvas.UI.Xaml.h>

#include "TimerHelper.h"
#include "fpscounter.h"
#include "HSVColorHelper.h"

Example H file

#pragma once

// these are only for the generated files from WinRT
#include "MainWindow.g.h"

#include <string>

#include <windows.h>

#include <winrt/Windows.Graphics.Display.h>
...
#include <winrt/Microsoft.Graphics.Canvas.UI.Xaml.h>

#include "Board.h"
#include "fpscounter.h"
#include "TimerHelper.h"

Testing

You should test (with 'using precompiled header' off and an empty pch.h that your files build correctly. Generated files and included Windows or WinRT files may not. Those are problems for my friends at Microsoft to fix.

Sources

Google C++ Style Guide, specifically
https://google.github.io/styleguide/cppguide.html#Names_and_Order_of_Includes
https://google.github.io/styleguide/cppguide.html#Windows_Code

[mgradwohl]

Old guidelines

In cpp files, include pch.h first (do not include pch.h in header files)
Local headers (in double quotes) are next.
Standard library headers (in angle brackets).
Traditional Windows SDK headers (eg: Windows.h)
Third-party library headers (e.g. gsl)
C++/WinRT projected namespace headers
e.g.
#pragma once
#include "pch.h"
#include "classheader.h"
#include
#include <windows.h>
#include "gsl/include/gsl"
#include <winrt/Windows.Foundation.h>