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digitalmars.D.learn - Wrapping C that uses compiler extensions

reply simendsjo <simen.endsjo pandavre.com> writes:
This code confuses me... It's from the c mysql windows dll, libmysql.dll.

   size_t (*snprintf)(struct charset_info_st *, char *to, size_t n,
                      const char *fmt,
                      ...) ATTRIBUTE_FORMAT_FPTR(printf, 4, 5);

#ifndef _my_attribute_h
#define _my_attribute_h

/*
   Disable __attribute__() on gcc < 2.7, g++ < 3.4, and non-gcc compilers.
   Some forms of __attribute__ are actually supported in earlier versions of
   g++, but we just disable them all because we only use them to generate
   compilation warnings.
*/
#ifndef __attribute__







#endif

/*
   __attribute__((format(...))) is only supported in gcc >= 2.8 and g++ 

= 3.4


   But that's already covered by the __attribute__ tests above, so this is
   just a convenience macro.
*/
#ifndef ATTRIBUTE_FORMAT

#endif

/*

    __attribute__((format(...))) on a function pointer is not supported
    until  gcc 3.1
*/
#ifndef ATTRIBUTE_FORMAT_FPTR





#endif


#endif
Mar 04 2011
parent reply =?UTF-8?B?IkrDqXLDtG1lIE0uIEJlcmdlciI=?= <jeberger free.fr> writes:
simendsjo wrote:

=20
 This code confuses me... It's from the c mysql windows dll, libmysql.dl=


l.

=20
   size_t (*snprintf)(struct charset_info_st *, char *to, size_t n,
                      const char *fmt,
                      ...) ATTRIBUTE_FORMAT_FPTR(printf, 4, 5);
=20


	You can safely ignore the =E2=80=9CATTRIBUTE_FORMAT_FPTR(printf, 4, 5)=E2=
=80=9D.
All it does is that it enables the compiler to check the format
string against the variable arguments and generate a warning if they
do not match.

		Jerome
--=20
mailto:jeberger free.fr
http://jeberger.free.fr
Jabber: jeberger jabber.fr
Mar 04 2011
parent reply simendsjo <simen.endsjo pandavre.com> writes:
On 04.03.2011 22:42, "Jérôme M. Berger" wrote:

 int main(string[] args) {
 	auto s1 =(); // MH MH
 	auto s2 =(); // OK
 	s2.c =ull; // OK
 	return 0;
 }


Is part of your message gone?


 You can safely ignore the “ATTRIBUTE_FORMAT_FPTR(printf, 4, 5)”.


That I understood :) Thanks!
Mar 04 2011
parent reply =?UTF-8?B?IkrDqXLDtG1lIE0uIEJlcmdlciI=?= <jeberger free.fr> writes:
simendsjo wrote:

 On 04.03.2011 22:42, "J=C3=A9r=C3=B4me M. Berger" wrote:

 int main(string[] args) {
     auto s1 =3D(); // MH MH
     auto s2 =3D(); // OK
     s2.c =3Dull; // OK
     return 0;
 }


=20
 Is part of your message gone?
=20


	Uh, I did not write that.


 You can safely ignore the =E2=80=9CATTRIBUTE_FORMAT_FPTR(printf, 4, 5)=




=E2=80=9D.

=20
 That I understood :) Thanks!


	Then if the issue is with the rest of the definition, it is more or
less equivalent to (you will need to translate the argument
declaration too):

alias size_t function (struct charset_info_st *, char *to, size_t n,
                       const char *fmt,
                       ...) snprintf;

		Jerome
--=20
mailto:jeberger free.fr
http://jeberger.free.fr
Jabber: jeberger jabber.fr
Mar 04 2011
parent reply simendsjo <simen.endsjo pandavre.com> writes:
On 05.03.2011 08:58, "Jérôme M. Berger" wrote:

 simendsjo wrote:

 On 04.03.2011 22:42, "Jérôme M. Berger" wrote:

 int main(string[] args) {
      auto s1 =(); // MH MH
      auto s2 =(); // OK
      s2.c =ull; // OK
      return 0;
 }


 Is part of your message gone?


 	Uh, I did not write that.


Checked the web newsinterface, and I see your post. In thunderbird I got 
another post from Tom with the subject "Struct reference returning 
function and const members" in your post...


 You can safely ignore the “ATTRIBUTE_FORMAT_FPTR(printf, 4, 5)”.


 That I understood :) Thanks!


 	Then if the issue is with the rest of the definition, it is more or
 less equivalent to (you will need to translate the argument
 declaration too):

 alias size_t function (struct charset_info_st *, char *to, size_t n,
                         const char *fmt,
                         ...) snprintf;

 		Jerome


The definition is inside a struct. I shouldn't use an alias then..?

This is the C struct:
typedef struct my_charset_handler_st
{
   // snip
   size_t (*snprintf)(struct charset_info_st *, char *to, size_t n,
                      const char *fmt,
                      ...) ATTRIBUTE_FORMAT_FPTR(printf, 4, 5);
   // snip
}

And this is my D struct:
struct my_charset_handler_st
{
   // snip
   size_t  function(charset_info_st*, char* to, size_t n,
                 const char* fmt,
                 ...) snprintf;
   // snip
}
Mar 05 2011
parent =?UTF-8?B?IkrDqXLDtG1lIE0uIEJlcmdlciI=?= <jeberger free.fr> writes:
simendsjo wrote:

 On 05.03.2011 08:58, "J=C3=A9r=C3=B4me M. Berger" wrote:

 simendsjo wrote:

 On 04.03.2011 22:42, "J=C3=A9r=C3=B4me M. Berger" wrote:

 int main(string[] args) {
      auto s1 =3D(); // MH MH
      auto s2 =3D(); // OK
      s2.c =3Dull; // OK
      return 0;
 }


 Is part of your message gone?


     Uh, I did not write that.


=20
 Checked the web newsinterface, and I see your post. In thunderbird I go=


t

 another post from Tom with the subject "Struct reference returning
 function and const members" in your post...
=20

 You can safely ignore the =E2=80=9CATTRIBUTE_FORMAT_FPTR(printf, 4, =








5)=E2=80=9D.

 That I understood :) Thanks!


     Then if the issue is with the rest of the definition, it is more o=




r

 less equivalent to (you will need to translate the argument
 declaration too):

 alias size_t function (struct charset_info_st *, char *to, size_t n,
                         const char *fmt,
                         ...) snprintf;

         Jerome


=20
 The definition is inside a struct. I shouldn't use an alias then..?
=20


	No, you are right, I thought there was a typedef in the C code...


 This is the C struct:
 typedef struct my_charset_handler_st
 {
   // snip
   size_t (*snprintf)(struct charset_info_st *, char *to, size_t n,
                      const char *fmt,
                      ...) ATTRIBUTE_FORMAT_FPTR(printf, 4, 5);
   // snip
 }
=20
 And this is my D struct:
 struct my_charset_handler_st
 {
   // snip
   size_t  function(charset_info_st*, char* to, size_t n,
                 const char* fmt,
                 ...) snprintf;
   // snip
 }


	Yes, that should be about right.

		Jerome
--=20
mailto:jeberger free.fr
http://jeberger.free.fr
Jabber: jeberger jabber.fr
Mar 05 2011