44. SLclass_set_pop_function

Synopsis

Set the pop callback for a new data type

Usage

int SLclass_set_pop_function (cl, pop_fun)

    SLang_Class_Type *cl
    int (*pop_fun) (unsigned char, VOID_STAR);

Description

SLclass_set_pop_function is used to set the callback for popping an object from the stack for a new data type specified by cl, which must have been previously obtained via SLclass_allocate_class.

The parameter pop_fun is a pointer to the pop callback function, which is required to take two arguments: an unsigned character representing the data type, and the address of the object to be popped. It must return zero upon success, or -1 upon failure.

SLclass_set_pop_function returns zero upon success, or -1 upon failure.

Example

The pop callback for SLANG_COMPLEX_TYPE looks like:

      static int complex_push (unsigned char type, VOID_STAR ptr)
      {
         double *z = *(double **) ptr;
         return SLang_pop_complex (&z[0], &z[1]);
      }

See Also

SLclass_allocate_class, SLclass_register_class