Name

XtCallCallbacks — execute the procedures in a widget’s callback list. 

Synopsis

void XtCallCallbacks(object, callback_name, call_data)

    Widget object;
    String callback_name;
    XtPointer call_data;

Arguments

objectSpecifies the object; may be of class Object or any subclass thereof. 

callback_name
Specifies the resource name of the callback list to be executed.

call_dataSpecifies the value to pass to each callback procedure as its third argument. 

Description

XtCallCallbacks is used to execute the callbacks in a given callback list.  The callback list is specified by resource name. 

The call_data argument is a (32-bit) longword.  The actual form of the data in the argument must be agreed on in advance by the callback function and the widget invoking it through XtCallCallbacks.  The longword can be used to represent an address if more data is to be passed to the callback procedure. 

If no data is needed, the call_data argument should be NULL.  (For example, the XtNcallback callback list in the Athena Command widget needs only to notify its clients that the button has been activated.  No data is passed in.) 

XtCallCallbacks ensures that if a callback procedure itself adds callbacks (with XtAddCallbacks), no unwanted recursion ensues. 

Callback lists are maintained in an internal compiled form.  Callback lists can be accessed outside the widget as resources but cannot be added, deleted, or invoked except through one of the Intrinsics functions (such as XtAddCallback) provided to access them.  The Intrinsics themselves make sure that resources of type Callback get compiled into this internal form. 

For more information on how to explicitly compile callbacks as resources of type XtRCallback, see XtConvertandStore. 

See Also

XtAddCallback(1), XtAddCallbacks(1), XtRemoveAllCallbacks(1), XtRemoveCallbacks(1),
XtCallbackProc(2).