On 2012-03-25 13:12, Bennie Copeland wrote:
Hello all. I'm sorry if this has been addressed before.
For a little background. I've been studying C++ with the intention of
doing cross platform work on Windows, OSX, and eventually iOS and some
other mobile OSes. My plan was to write cross platform shared libraries
for the core functionality and implement the GUI using Win32, Cocoa,
etc. Well, while C++ is powerful, I'm finding it a beast to work with. I
kept thinking about abandoning C++ altogether and using C# with Mono
until I stumbled upon D. D sounds exactly like what I am looking for,
powerful yet productive and native.
First I have to say that D is a great language for doing cross platform
development.
But for iOS there are a couple of big problems. The reference D
compiler, DMD, does not have an ARM-backend. There are other compilers
available though: LDC, the DMD frontend on the LLVM backend and GDC, the
DMD frontend on the GCC backend. Second big problem is the D runtime
does not support ARM. As far as I know, no one has ever used D on iOS.
My question however is how to do D cross platform development. I can't
seem to find any recent information about it. From what I have gathered
so far it seems, shared libraries are possible on win/osx/linux, but
only when linked against other D code. For linking against C, I can
create a DLL in windows, but I can't create an .so in linux, and no
information at all about OSX. Some of the information I found is years
old and I can't tell if the situation has changed. There is nothing in
the FAQ about libraries. And googling provides little information.
You should be able to create shared libraries for linking with C code.
You just need to make sure you initialize the D runtime. I'm not
entirely sure about the status for creating shared libraries, not sure
if the runtime has been modified to support that on all platforms. I
think Windows and Linux is good to go but I don't think the runtime is
not ready yet for Mac OS X.
So, is it possible to write the core of an application in a cross
platform D library that can be callable by C, C++, or Objective-C to
provide the GUI elements?
If not, is it possible to write a C wrapper around the library that is
then callable by C, C++ or Objective-C?
How have others approached this situation?
Besides the library issues, what other issues or gotchas should I look
out for in regards to cross platform development?
When it comes to providing a GUI for your application there are a couple
of choices:
* Directly access the native GUI operations of the operating system
* Use a cross platform GUI library
For directly accessing the native GUI of the operating system there are
again various options.
First option, C wrapper. A C wrapper works for all languages you need to
interact with: C, C++ and Objective-C.
D has limited support for interfacing directly with C++. For example, D
understand the C++ mangling and you can call virtual C++ functions from
D. This could be another idea, or used together with C wrappers.
http://dlang.org/cpp_interface.html
For interfacing with Objective-C there are a couple of options as well.
One option is to use C wrappers. Another is to use the Objective-C
runtime functions to get be able to create Objective-C class and methods
from D. There are two projects that have gone this road and created a
fully working, fully automatic bridge between D and Objective-C.
Although it turned out to not be usable in practice.
A third option for Objective-C would be to use a fork of DMD that makes
it possible to directly interface with Objective-C, just as it's
possible with C. I'm not sure of the status of this project but an alpha
has been released.
D/Objective-C bridge: http://dsource.org/projects/dstep
D/Objective-C bridge: http://michelf.com/projects/d-objc-bridge/
DMD fork: http://michelf.com/projects/d-objc/
Cross platform GUI libraries. Here are again several options:
* DWT - Port of SWT. Uses the native operations of the operating system.
Supports Windows (win32) and Linux (GTK+). Support for Mac OS X (Cocoa)
is worked on.
http://dsource.org/projects/dwt
* gtkD - Bindings to GTK. Does not use the native drawing operations of
the operating system. Available on all platforms.
http://dsource.org/projects/gtkd
* QtD - Bindings to Qt. Use the native drawing operations of the
operating system (I think). Available on all platforms. Not sure if this
is developed any more.
http://dsource.org/projects/qtd
* wxD - Bindings to wxWidgets. Use the native drawing operations of the
operating system. Available on all platforms. Not sure of the status.
http://wxd.sourceforge.net/
--
/Jacob Carlborg
