Kenwood HP 9000 manual Example a Common Initializer for Multiple Libraries, Output of testlib

Shared Library Management Routines

Initializers for Shared Libraries

if (shl_findsym(&hndl_foo, “in_to_cm”, TYPE_PROCEDURE, (void *) &in_to_cm))

perror(“shl_findsym: error finding in_to_cm”), exit(1);

if (shl_findsym(&hndl_foo, “gal_to_l”, TYPE_PROCEDURE, (void *) &gal_to_l))

perror(“shl_findsym: error finding gal_to_l”), exit(1);

if (shl_findsym(&hndl_foo, “oz_to_g”, TYPE_PROCEDURE, (void *) &oz_to_g))

perror(“shl_findsym: errror finding oz_to_g”), exit(1);

/*

*Call routines from libfoo.sl:

*/

printf(“1.0in = %5.2fcm\n”, (*in_to_cm)(1.0)); printf(“1.0gal = %5.2fl\n”, (*gal_to_l)(1.0)); printf(“1.0oz = %5.2fg\n”, (*oz_to_g)(1.0)); /*

*Unload the library:

*/

shl_unload(hndl_foo);

}

The following is the output of running the testlib program:

Output of testlib

libfoo loaded 1.0in = 2.54cm 1.0gal = 3.79l 1.0oz = 28.35g libfoo unloaded

Example: A Common Initializer for Multiple Libraries

Rather than have a unique initializer for each library, libraries could have one initializer that calls the actual initialization code for each library. To use this technique, each library declares and references the same initializer (for example, _INITIALIZER), which calls the appropriate initialization code for each library.

This is easily done by defining load and unload functions in each library. When _INITIALIZER is called, it uses shl_findsym to find and call the load or unload function (depending on the value of the loading flag).

The following example shows the source for an _INITIALIZER function:

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