TutOptionChangeCbLookup

T_CB TutOptionChangeCbLookup(option, change_func, arg) 
T_OPTION option; 
T_OPTION_CHANGE_CB_FUNC change_func; 
T_CB_ARG arg;

Arguments

option — option to look up the change callback for; NULL if looking up a global callback (for all options)

Return Values

Diagnostics

If TutOptionChangeCbLookup fails, it returns NULL and sets the global SmartSockets error number to one of:

Description

TutOptionChangeCbLookup returns the callback registered with TutOptionChangeCbCreate, if any. The arguments, option, change_func, and arg, must match precisely those used in TutOptionChangeCbCreate for the call to be successful.

Caution

See Also

Examples

/* This callback function is called when the value of option "bool_opt" changes. */ 
void T_ENTRY BoolChanged(option, data, arg) 
T_OPTION option; 
T_OPTION_CHANGE_CB_DATA data; 
T_CB_ARG arg; 
{ 
  T_BOOL bool_return; 
 
  if (!TutOptionGetBool(option, &bool_return)) { 
    /* error */ 
  } 
  if (bool_return) { 
    TutOut("Value of option %s is TRUE\n", 
             TutOptionGetName(option)); 
  }  
  else { 
    TutOut("Value of option %s is FALSE\n", 
             TutOptionGetName(option)); 
  }  
} /* BoolChanged */ 
 
/* Below is a code fragment that could go into  */ 
/* an initialization routine.                   */ 
T_OPTION option; 
T_CB cb, bool_cb; 
 
option = TutOptionCreate("bool_opt", T_OPT_TYPE_BOOLEAN); 
if (option == NULL) { 
  /* error */ 
} 
 
cb = TutOptionChangeCbCreate(option, BoolChanged, NULL); 
if (cb == NULL) { 
  /* error */ 
} 
 
bool_cb = TutOptionChangeCbLookup(option, BoolChanged, NULL); 
if (bool_cb != cb) { 
  /* error */ 
}