session_encode() just return the session dataset in a formatted form

session_start();

$_SESSION['login_ok'] = true;
$_SESSION['nome'] = 'sica';
$_SESSION['inteiro'] = 34;

echo session_encode();

this code will print

login_ok|b:1;nome|s:4:"sica";inteiro|i:34;

session_encode() can't handle pipes in your keys.

<?php
session_start();
$_SESSION = ['foo|bar'=>'ba;z']; pathetic
dump(session_encode()); // false because "foo|bar" contains a pipe
?>

The session_encode and session_decode functions are incomplete.

Because there is no option to collect the output values for session_decode  or input an array in session_encode.

I faced this issue while trying to implement custom session using session_set_save_handler.

It led me to limit the functionality to particular serialize_handler and had to hardcode the encode and decode functions like serialize and unserialize for option ['serialize_handler' => 'php_serialize'] instead of session_encode and session_decode once i am done with defining the encoding algo.