Re: [Help-glpk] Re: libglpk0: excessive install dependencies

[Andrew Makhorin]

Vijay,

Thank you for your efforts.

I think the dynamic linking of mysql and odbc dll's for a ms windows
version of the package can be easily implemented, because such
version does not need a configure script (I mean the version compiled
with some native w32 compiler like vc6). Thus, it is sufficient to
enclose the corresponding fragment within #ifdef/#endif and add
necessary -D options in the makefile.

Btw, dynamic loading/unloading can be performed in DllMain; see
file glplib03.c; probably it is a most appropraite place for that.

Andrew Makhorin


> It would be nice to have this change (i.e. explicitly loading the
> dynamic library/shared object related to table feature in MathProg)
> work on MS Windows.

> I ported example on page http://linux.die.net/man/3/dlopen to
> windows. We will need to use ifdefs at come places (loading,
> unloading, and getting function address), but actual function
> invocation is OS independent. I have tested program below on Windows
> XP and it works as expected. 

> ---------------------------------------------
> #include<stdio.h>
> #include<stdlib.h>

> #define WINDOWS /* Testing purpose only */

> #ifdef WINDOWS
> #include<windows.h>
> #endif

> int main(int argc, char **argv) {

> #ifdef LINUX
>     void *handle;
>     char *error;
> #else ifdef WINDOWS
>     HINSTANCE handle; 
> #endif

>     /* Note: OS Indepdent code. */
>     double (*cosine)(double);    

> #ifdef LINUX
>     handle = dlopen ("libm.so", RTLD_LAZY);
>     if (!handle) {
>         fprintf (stderr, "%s\n", dlerror());
>         exit(1);
>     }

> #else ifdef WINDOWS

>     //handle = LoadLibrary(TEXT("libmySQL"));
>     //handle = LoadLibrary(TEXT("odbc32"));
>     handle = LoadLibrary(TEXT("msvcrt"));
>     if(!handle) {
>         fprintf(stderr, "Could not load shared library msvcrt.dll.\n");
>         exit(1);
>     }
> #endif

> #ifdef LINUX
>     dlerror();    /* Clear any existing error */    
>     cosine = dlsym(handle, "cos");

>     if ((error = dlerror()) != NULL)  {
>         fprintf (stderr, "%s\n", error);
>         exit(1);
>     }

> #else ifdef WINDOWS
>     cosine = (void*)GetProcAddress(handle, "cos");
>     if(!cosine) {
>         fprintf(stderr, "Could not find function  #39;cos #39; in dll.\n");

>     }
> #endif

>     /* Note: OS Indepdent code. */
>     printf ("%f\n", (*cosine)(2.0));
>     
> #ifdef LINUX
>     dlclose(handle);

> #else if WINDOWS
>     FreeLibrary(handle);
> #endif

>     return 0;
> }

> On Tue, Mar 11, 2008 at 1:48 AM, Andrew Makhorin <address@hidden> wrote:
>> I found a guide for the program changes needed at
>> http://linux.die.net/man/3/dlopen
>> According to
>> http://sourceware.org/autobook/autobook/autobook_167.html
>> Configure.ac also will need changes: At least AC_LIBTOOL_DLOPEN must
>> be included.

>> Do You know of better guides for shared libraries?



> Please see:
> http://www.gnu.org/software/libtool/manual.html

>> I will try to make an implementation until Sunday March 17th.








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