Monday, December 04, 2006

sourcefiles and namespaces again

I was a little brief on my previous post about sourcefiles, namespaces and imports. I'll try to explain it a bit more here. So here's an example of multiple sourcefiles working together.

# File "someDir/MyApp/GUI/mainwindow.hyp"
namespace MyApp.GUI

class MainWindow
# (...)

# File "someDir/MyApp/Data/store.hyp"
namespace MyApp.Data

class DBStorage
# (...)

# File "someDir/MyApp/Core/main.hyp"
namespace MyApp.Core

import MyApp.GUI.mainwindow

static class Main
static procedure main()
# main program's entry point
var dbs : MyApp.Data.DBStorage
var win : MyApp.GUI.MainWindow
# (...)
I hope this clears it up. Every file is in a namespace. When you import a file you need to specify the namespace AND the name of the file you want to use. The classes inside a file are in the namespace of that file, so that's why the "main()" code uses the full names like "MyApp.Data.DBStorage" instead of just "DBStorage". To get rid of the long names I will support 'using' declarations (in fact aliases), but that's for later.

Something we don't support now is having public/private members in a sourcefile. The Main class of the example above does not have to be public. For now all direct source file members are simply public.

A program often needs to use libraries outside of its own codebase. Therefore Hyper will support some variation of the 'class path' concept from Java but with a different name. I suggest somethink like 'codebase path' or 'code path'. The default 'code path' will be empty and this means the compiler will only look at the sources you are compiling now (including the imported files from the same codebase). How about closed source libraries? I am thinking to use a concept similar to D's interface files (see the end of this page). This means having a second type of sourcefile that only contains the interface parts of each class (the procedure headers etc...).

* I am tempted to have the compiler generate C++. This would be somewhat easier than using LLVM, but it would require an extra compilation to get a working program. It could be an acceptable temporary solution.
* The next compiler release will support public/private access checking, full 'const' checking and maybe also 'static' checking. But I am unsure about going for a small or a major release. A major release take much longer to be released, but allows for large internal improvements in the compiler. A minor release would be version 0.3.31, and a major release would be 0.4.0.
* Restricted pointers will definately be part of the language. I just don't know yet when to start implementing it and whether or not to wait after the next major release (0.4.0). I would like to have a better name for them. "References" is a candidate, but it could be too confusing for C++ users that don't know yet what they really are, since they differ a lot from the 'references' from C++.
* Strict in/inout parameters will probably be added when restricted pointers are already implemented.

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