g_datalist_id_replace_data (
  GData** datalist,
  GQuark key_id,
  gpointer oldval,
  gpointer newval,
  GDestroyNotify destroy,
  GDestroyNotify* old_destroy


Compares the member that is associated with key_id in datalist to oldval, and if they are the same, replace oldval with newval.

This is like a typical atomic compare-and-exchange operation, for a member of datalist.

If the previous value was replaced then ownership of the old value (oldval) is passed to the caller, including the registered destroy notify for it (passed out in old_destroy). Its up to the caller to free this as he wishes, which may or may not include using old_destroy as sometimes replacement should not destroy the object in the normal way.

Available since:2.34


datalist GData

Location of a datalist.

 The data is owned by the caller of the function.
key_id GQuark

The GQuark identifying a data element.

oldval gpointer

The old value to compare against.

newval gpointer

The new value to replace it with.

destroy GDestroyNotify

Destroy notify for the new value.

old_destroy GDestroyNotify

Destroy notify for the existing value.

 The argument will be set by the function.
 The argument can be NULL.
 The data is owned by the caller of the function.

Return value

Returns: gboolean

TRUE if the existing value for key_id was replaced by newval, FALSE otherwise.