how to use session_set_save_handler dynamically?
<p>I want that session_set_save_handler can be used two times and it dynamically works.
but I found like this:</p>

<ol>
<li>session_set_save_handler (first time, success);</li>
<li>session_start</li>
<li>...</li>
<li>session_set_save_handler (second time, fail)</li>
<li>...</li>
</ol>

<p>here  I found that if I move the 'session_start' from (2) to (4), the second session_set_save_handler will work.</p>

<p>But what I need is that both work.</p>
