public override string toStr()
{
if (m_size == 0) return "[,]";
StringBuilder s = new StringBuilder(32+m_size*32);
s.Append("[");
for (int i=0; i<m_size; i++)
{
if (i > 0) s.Append(", ");
if (m_values[i] == null) s.Append("null");
else s.Append(m_values[i]);
}
s.Append("]");
return s.ToString();
}