How can I force the current object to overwrite itself?

Question

PHP

Added tags Javaand C++, because I wonder if something similar is possible in other OOP languages.
Such a class:

<?php
class DB {
  private $link;
  private $config;
  private $charset;

  function __construct($config, $charset) {
    # линки
    $link = &$this->link;
    # сохранение аргументов
    $this->config  = $config;
    $this->charset = $charset;
    # подключение к СУБД
    $link = new mysqli($config['host'], $config['username'], $config['password']);
    # установка БД
    $this->SetDB($config['dbname']);
    # установка кодировки
    $this->SetCharset($charset);
  }

  function SetDB($dbname) {
    # ...
  }

  function SetCharset($charset) {
    # ...
  }

  function Reconnect() {
    # линки
    $config  = &$this->config;
    $charset = &$this->charset;
    # перезапись объекта
    $this = new self($config, $charset);
  }
# ...
}

The call to Reconnect() must overwrite the current object.

$db = new DB($MySQLConfig, $charset);
# ...
$db->Reconnect();

But instead:

PHP Fatal error:  Cannot re-assign $this in /class/DB.php

The problem can be solved like this: $db = $db->Reconnect();
But this is not concise and makes it difficult to use the method.
UPD:
I'm not sure, but it should work like this:

function Reconnect() {
  # линки
  $config  = &$this->config;
  $charset = &$this->charset;

  # перезапись объекта
  $this->__construct($config, $charset);
}

Does not cause errors.

Answer 1

In telepathy mode, I guess what you want to implement. Apparently, we are talking about a completely standard mechanism for generating a connection object from a database object.
To understand how such bicycles are built, look into the code of any ORM or, in general, any OOP wrapper over a database driver. In most cases, you will see the following picture:
1. The database configuration is a factory (yes, yes, the very patterns that neophytes NEED ).
2. The method connectreturns a connection object.
3. The connection object (except for query execution methods) has a method closethat closes the connection (an attempt to execute a query on a closed connection will generate an error).
4. The connection (as an object) lives once and cannot be reopened after being closed. But you can always open a new connection from the database factory.
Why so:
The main principle of OOP: a separate concept - a separate class. The database (on the client side) is only a configuration: server address, username, password, database name and other parameters. A database connection is a separate entity through which transactions are created and cursors (separate entities) through which queries are executed. The result of query execution is a separate entity. A single row in a selection is a single entity (unless it's a tuple). And only individual fields in a row have primitive data types.