TutPtrAryChangeCbCreate

Name

TutPtrAryChangeCbCreate — create a callback that is called when a pointer array changes

Synopsis

T_CB TutPtrAryChangeCbCreate(ptr_ary, change_func, arg) 
T_PTR_ARY ptr_ary; 
T_PTR_ARY_CHANGE_CB_FUNC change_func; 
T_CB_ARG arg;

Arguments

ptr_ary — pointer array to register the change callback for

change_func — callback function

arg — callback function argument

Return Values

New callback if successful, NULL otherwise.

Diagnostics

If TutPtrAryChangeCbCreate fails, it returns NULL and sets the global SmartSockets error number to:

T_ERR_NULL_PTR — ptr_ary or change_func argument was NULL

T_ERR_ALREADY_EXISTS — a callback with change_func and arg already exists

Description

TutPtrAryChangeCbCreate attaches the change_func callback to ptr_ary. When an item in ptr_ary is inserted or removed, change_func is called with three arguments:

ptr_ary — pointer array whose item changed

data — pointer to callback data structure

arg — callback function argument

Caution

The T_ENTRY declaration specifier is required in the definition of all callback functions in addition to their prototypes.

Examples

This example displays output when a pointer array changes:

void T_ENTRY PtrAryChanged(ptr_ary, data, arg) 
T_PTR_ARY ptr_ary; 
T_PTR_ARY_CHANGE_CB_DATA data; 
T_CB_ARG arg; 
{ 
  TutOut("Pointer array change reason is %d.\n", data->reason); 
} /* PtrAryChanged */ 
. 
. 
. 
T_CB cb;  
 
cb = TutPtrAryChangeCbCreate(ptr_ary, PtrAryChanged, NULL); 
if (cb == NULL) { 
  /* error */ 
}