Cacher is the code snippet organizer for pro developers

Source code

For 1.5.x-only libraries, the source code resides in the src folder. For example:

Servo/src/Servo.h
Servo/src/Servo.cpp

The source code found in src folder and all its subfolders is compiled and linked in the user’s sketch. Only the src folder is added to the include search path (both when compiling the sketch and the library). When the user imports a library into their sketch (from the "Tools > Import Library" menu), an #include statement will be added for all header (.h) files in the src/ directory (but not its subfolders). As a result, these header files form something of a de facto interface to your library; in general, the only header files in the root src/ folder should be those that you want to expose to the user's sketch and plan to maintain compatibility with in future versions of the library. Place internal header files in a subfolder of the src/ folder.

For backward compatibility with Arduino 1.0.x, the library author may opt to not place source code into a folder called src. In this case the 1.0 library format is applied and the source code is searched from the library root folder and the utility folder, for example:

Servo/Servo.h
Servo/Servo.cpp
Servo/utility/ServoTimers.h
Servo/utility/ServoTimers.cpp

This will allow existing 1.0.x libraries to compile under 1.5.x as well and vice-versa. If a library only needs to run on 1.5.x, we recommend placing all source code in the src/ folder. If a library requires recursive compilation of nested source folders, its code must be in the src/ folder (since 1.0.x doesn’t support recursive compilation, backwards compatibility wouldn’t be possible anyway).