Okay, so what has been shared is that the first step is to get C
to call D, because if I can do that, then I can get Obj C to call
C since there's no direct bridge to D. Obj C has a way to call C.
So, I found this article:
http://www.prowiki.org/wiki4d/wiki.cgi?DcalledFromC
I also found it's not quite up to date with the latest DMD. Here
are some things I didn't have to do:
* If you scroll to the bottom, it talks about needing a main() in
D. That's no longer necessary. So, the file in the example
Dmaindummy.d is no longer required. This meant that I could edit
Cmain.c and remove the print line there because it was irrelevant.
* One needs to use phobos2 instead of phobos. On Ubuntu 14.04, I
did apt-get install dmd to get the D compiler, and then did
apt-cache search libphobos to see which one was the latest it
had, and then in my case I did apt-get install libphobos2-69, but
your situation may vary.
* This changes the compilation a little, and I lowercased the
filenames to make it easier for me:
$ dmd -c dfunc.d
$ gcc cmain.c dfunc.o -o ctest -lphobos2 -lpthread -lm
I then could call ctest with:
$ ./ctest
Note on OSX, the GCC line is a little different. If you've
installed dmd from homebrew, it doesn't write to /usr/lib (that's
locked down now) but does write to /usr/local/lib and
/usr/local/include. So, you have to tell GCC to call that path
with the -L parameter because it doesn't do that by default for
some strange reason on OSX:
$ gcc cmain.c dfunc.o -o ctest -L/usr/local/lib -lphobos2
-lpthread -lm
This then made it find /usr/local/lib/libphobos2.a with that
-lphobos2 parameter.
So, then it worked on OSX too.
And now to figure out how to make a C library instead of an
executable, and then how to load that compiled library in
Objective C, load a header (.h file) in Objective C for that C
function, and call the C function, which then calls the D
function.
I'll update you if I figure all that out...
