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Header Files

Header Files are a special file type that allows the collection of Import and Using Declarations, Operators and Type aliases. They are created with the .dyh or .dyvilh file extension and allow the definition of the above header elements, but not classes. To use header files from within other files, one can include them with the using keyword. This has the same effect as copying the code from the header into the source file:
import java.util.List
import java.util.ArrayList
using MyHeader
class MyClass
static func main(args: [String]) -> void
let list: List<String> = new ArrayList<String> // no explicit import required
Header Files differ from other class files in that they are not compiled to .class files, but to an object code representation with the .dyo file extension. The file type stores all import and using declarations, operator definitions and type aliases in a binary format. This ensures that the entire source code of the Header File (excluding comments) can be rebuilt from the object code.