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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__
# if !defined(__GNUC__)
#  define __attribute__(A)
# elif GCC_VERSION < 2008
#  define __attribute__(A)
# elif defined(__cplusplus) && GCC_VERSION < 3004
#  define __attribute__(A)
# endif
#endif

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

= 3.4



   just a convenience macro.
*/
#ifndef ATTRIBUTE_FORMAT
# define ATTRIBUTE_FORMAT(style, m, n) __attribute__((format(style, m, n)))
#endif

/*

    __attribute__((format(...))) on a function pointer is not supported
    until  gcc 3.1
*/
#ifndef ATTRIBUTE_FORMAT_FPTR
# if (GCC_VERSION >= 3001)
#  define ATTRIBUTE_FORMAT_FPTR(style, m, n) ATTRIBUTE_FORMAT(style, m, n)
# else
#  define ATTRIBUTE_FORMAT_FPTR(style, m, n)
# endif /* GNUC >= 3.1 */
#endif


#endif
Mar 04 2011
parent reply =?UTF-8?B?IkrDqXLDtG1lIE0uIEJlcmdlciI=?= <jeberger free.fr> writes:
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

simendsjo wrote:

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




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



=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:
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

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?
=20





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







=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?






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:
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

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?






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




 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, =













 That I understood :) Thanks!



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







 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..?
=20





 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
 }




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