'Handle column attribute changed notifications from columns that are
members of this `ColDefs`.
`ColDefs` itself does not currently do anything with this, and just
bubbles the notification up to any listening table HDUs that may need
to update their headers, etc.  However, this also informs the table of
the numerical index of the column that changed.'

def _update_column_attribute_changed(self, column, attr, old_value, new_value):

    idx = 0
    for (idx, col) in enumerate(self.columns):
        if (col is column):
            break
    if (attr == 'name'):
        del self.names
    elif (attr == 'format'):
        del self.formats
    self._notify('column_attribute_changed', column, idx, attr, old_value, new_value)
