On Saturday, 2 November 2019 at 18:31:28 UTC, Stefan Koch wrote:
On Saturday, 2 November 2019 at 17:49:09 UTC, Luh wrote:
Hello,
When trying to pass a D function to the C callback, the
compiler says:
'Error: cannot implicitly convert expression &this.onProcessCb
of type extern (C) bool delegate(const(short*) a, ulong b,
void* c) to extern (C) bool function(const(short*), ulong,
void*'
because my function is member of a class (compiles when the
function is out of the class).
Is there any way to say to solve this ?
The wiki isn't very clear about the C callbacks:
https://dlang.org/spec/interfaceToC.html#callbacks
C code:
----
typedef bool (*onProcessCallback)(const short*, size_t, void*);
----
D Code:
-----
class Game
{
onProcessCallback m_onProcessCb;
this()
{
m_onProcessCb = &onProcessCb; // Error here
}
void onProcess()
{
// ...
}
extern(C) bool onProcessCb(const short* a, size_t b, void* c)
{
onProcess();
return true;
}
}
private extern(C)
{
// Should call onProcess() when executed by the C lib
alias onProcessCallback = bool function(const short*, size_t,
void*);
}
-----
you are missing a static in your member function's signature.
The callback is not providing a this pointer.
My problem is, that the onProcess function should not be static
because it uses a variable inside the class.
like:
-----
class Game
{
private short[] m_a;
void onProcess(short[] a)
{
m_a ~= a;
// ...
}
extern(C) bool onProcessCb(const short* a, size_t b, void* c)
{
onProcess();
return true;
}
}
-----
So I think I just can't. :(
