TutCbSetFunction

T_BOOL TutCbSetFunction(cb, func) 
T_CB cb; 
T_CB_FUNC func;

Arguments

Return Values

Diagnostics

Description

TutCbSetFunction changes the callback function referenced by cb to func. It is useful for situations where the purpose of a callback has changed, but the need for the callback still exists. This capability eliminates the need to destroy and recreate a new callback just to change the purpose of the callback.

This function uses the generic callback function definition, so it is usually necessary to cast any type-specific callback function to the generic T_CB_FUNC for use with this function. This results in some loss of type checking, but greater flexibility.

Caution

See Also

Examples

This example creates a callback and then alternates between two functions for the callback function:

static void T_ENTRY time_change_cb_odd(dummy, data, arg) 
T_PTR dummy; /* always NULL */ 
T_TIME_CHANGE_CB_DATA data; 
T_CB_ARG arg; 
{ 
  T_CB_FUNC cb_func; 
 
  /* Forward declaration of the other callback function so the */ 
  /* compiler will recognize this symbol */ 
  extern T_TIME_CHANGE_CB_FUNC time_change_cb_even; 
 
  TutOut("Time change odd callback called\n"); 
  /* Make sure the callback function is set properly. */ 
  if (!TutCbGetFunction(data, &cb_func)) { 
    /* error */ 
  } 
  if (cb_func != (T_CB_FUNC)time_change_cb_odd) { 
    /* error */ 
  } 
  if (!TutCbSetFunction(data->cb, (T_CB_FUNC)time_change_cb_even)) 
{ 
    /* error */ 
  } 
} 
 
static void T_ENTRY time_change_cb_even(dummy, data, arg) 
T_PTR dummy; /* always NULL */ 
T_TIME_CHANGE_CB_DATA data; 
T_CB_ARG arg; 
{ 
  T_CB_FUNC cb_func; 
  TutOut("Time change even callback called\n"); 
  /* Make sure the callback function is set properly. */ 
  if (!TutCbGetFunction(data, &cb_func)) { 
    /* error */ 
  } 
  if (cb_func != (T_CB_FUNC)time_change_cb_even) { 
    /* error */ 
  } 
  if (!TutCbSetFunction(data->cb, (T_CB_FUNC)time_change_cb_odd)) 
{ 
    /* error */ 
  } 
} 
 
if (TutTimeChangeCbCreate(time_change_cb_even, NULL) == NULL) { 
  /* error */ 
}