Ease of calling C code from D

[Atila Neves]

One of D's marketed advantages it its compatibility with C. The C 
standard library is even included! However, after having played 
around with this quite a bit last week trying to call legacy C 
code from D, the one thing that put me off and made me think that 
C++ is better for this for my team is the C preprocessor. 
Unfortunately a lot of C code has macros that call macros that 
call other macros, and the only way to properly get around it is 
to hand-translate them one by one.

There is htod but it's Windows only. I tried running it with 
Wine, it didn't work right off the bat and if I had to go check 
out why it didn't work I wasn't going to convince anyone at work 
so I didn't bother. Also, from what I read here on the site I'm 
sure it'd choke on the macros as well.

I know that having a fully-featured C preprocessor in a D 
compiler is a bad idea for several reasons, but in C++ it's 
#include "cheader.h" and, assuming one sets all the revelant -I 
flags to the compiler, that's that. That really is a massively 
important feature (with its downsides, I know).

For popular C libraries there's Deimos (and even then _somebody_ 
has to go to the work and make sure it compiles), but for legacy 
code...

I guess my point is I'm glad I can call C code from D if I really 
have to, but that I'd also think about it twice given the 
interface issues. Another problem I had was the silly C code 
taking char* instead of const char*. Passing in D strings was 
"fun".

Atila