Sets the comparison function used when sorting to be sort_func. If the current sort column id of sortable is the same as sort_column_id, then the model will sort using this function.
the sort column id to set the function for
The comparison function
User data to pass to sort_func, or NULL
Destroy notifier of user_data, or NULL
Sets the comparison function used when sorting to be sort_func. If the current sort column id of sortable is the same as sort_column_id, then the model will sort using this function.