Hi,

In my application, I want to be able to extand it using regular C
objects, loaded using for example dlfcn for POSIX systems (maybe
another way on Windows).
So, I need to have C functions pointers but I don't know how to declare
them correctly :

/////////// test.d ///////////

module test;

extern(C){
    int c_function(int param){
        return param;
    }
}

int main(){
    // create a pointer to c_function
    extern (C) int function(int) ptr = &c_function;
    extern (C) int (*ptr2)(int)      = &c_function;
    return 0;
}

//////////////////////////////

$ dmd test.d
test.d(35): cannot implicitly convert expression (& c_function) of type
int(C *)(int param) to int(*)(int)
test.d(36): cannot implicitly convert expression (& c_function) of type
int(C *)(int param) to int(*)(int)

So, How do we do that , I did not find neither on the documentation nor
while browsing the web for the solution.
Thanks

Mildred

-- 
Mildred       <xmpp:mildred@jabber.fr> <http://mildred632.free.fr/> Clef GPG :    <hkp://pgp.mit.edu> ou <http://mildred632.free.fr/gpg_key> Fingerprint : 197C A7E6 645B 4299 6D37 684B 6F9D A8D6 [9A7D 2E2B]

Mildred wrote:
> Hi,
> 
> So, I need to have C functions pointers but I don't know how to declare
> them correctly :

It's easiest to typedef them; the typedef picks up the extern(C).

> module test;
> 
> extern(C){
>     int c_function(int param){
>         return param;
>     }
> }

extern (C) {
  typedef int function(int) CFuncPtr;
}

void main() {
   CFuncPtr ptr = &c_function;
}


BTW, this type of question really belongs in the 'D.learn' newgroup.

> extern (C) {
>    typedef int function(int) CFuncPtr;
> }
> 
> void main() {
>     CFuncPtr ptr = &c_function;
> }
> 
> 
> BTW, this type of question really belongs in the 'D.learn' newgroup.

Thanks for the answer,
I didn't knew in which newsgroup I had to post, so I posted here,
thanks for that clarification. I'll post there the next time.

Mildred
-- 
Mildred       <xmpp:mildred@jabber.fr> <http://mildred632.free.fr/> Clef GPG :    <hkp://pgp.mit.edu> ou <http://mildred632.free.fr/gpg_key> Fingerprint : 197C A7E6 645B 4299 6D37 684B 6F9D A8D6 [9A7D 2E2B]

Don Clugston wrote:
> Mildred wrote:
>> Hi,
>>
>> So, I need to have C functions pointers but I don't know how to declare them correctly :
> 
> It's easiest to typedef them; the typedef picks up the extern(C).

Or alias them.

>> module test;
>>
>> extern(C){
>>     int c_function(int param){
>>         return param;
>>     }
>> }
> 
> extern (C) {
>   typedef int function(int) CFuncPtr;
> }
<snip>

I see.  So

    extern (C) int function(int) ptr = &c_function;

merely gives the symbol ptr C linkage, and doesn't affect the linkage of the function involved?

There ought to be a way of giving function pointer types linkage attributes inline.  Maybe

    int extern (C) function(int) ptr = &c_function;

or something...?

Stewart.

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