On Saturday, 4 November 2023 at 03:00:49 UTC, Dadoum wrote:
I was wondering why C++ linkage forbids strings as arguments
while we can with the C one.
With C linkage, it's translated to a template that's defined in
the automatically generated header, but it just doesn't compile
in C++.
`extern(C++)` functions use C++ name mangling, which includes the
types of the parameters in the mangled name. However, since C++
does not have a built-in slice type like D's `T[]`, there is no
valid C++ mangling for a D slice. Because of this, it is
impossible to compile an `extern(C++)` function that has a D
slice as a parameter.
As a workaround, you can convert the slice to a `struct`:
```d
struct DSlice(T)
{
T* ptr;
size_t length;
T[] opIndex() => ptr[0 .. length];
}
DSlice!T toDslice(T)(T[] slice)
{
return DSlice!T(slice.ptr, slice.length);
}
extern(C++) void hello(DSlice!(const(char)) arg)
{
import std.stdio;
writeln(arg[]);
}
void main()
{
const(char)[] greeting = "hello";
hello(greeting.toDslice);
}
```
