On 05/23/2010 12:16 AM, Mike Parker wrote:
Walter Bright wrote:
Robert Clipsham wrote:
On 22/05/10 17:42, Andrei Alexandrescu wrote:
- Interfacing to C libraries is now overly complex thanks to const
correctness. After updating all the function signatures I found phobos
was completely lacking the functions to convert between C and D
strings
of varying constness or with different encodings
(char/wchar/dchar).. I
ended up writing my own functions
Could you please give more detail on that? There should be essentially
no problem with using C-style strings with D regardless of constness.
extern(C)void someFunc(char*);
There is no function in phobos which will allow me to call this
function using a D string, toStringz() gives:
test.d(4): Error: function test.someFunc (char*) is not callable
using argument types (const(char)*)
Unless I cast away const, which isn't pretty if you've got a lot of
these functions, unless you write a wrapper for each one (my current
hack). to!() doesn't support it at all, and I can't find another
method in phobos for it.
What's necessary is to decide if someFunc changes the string data or
not. If it does not, then it should be prototyped as:
extern (C) void someFunc(const char *);
If it does, then the char* is the correct declaration, and an
immutable string should not be passed to it.
That's not the problem. The problem is this:
const(char)* toStringz(const(char)[] s);
There's no equivalent for:
char *toStringz(char[] s);
Hence the need to cast away const or use a wrapper for non-const char*
args.
Yah, and that's intentional. APIs that use zero-terminated strings for
output are very rare and most often inherently unsafe.
Andrei
