Q:

Loading an object from PHP session, does it call constructor?

If I save some object in a php session variable $_SESSION['geoip'] = new GeoIP(); and then on future page loads I use $geoip = $_SESSION['geoip'], will it call the constructor?
My constructor for that GeoIP class is making a call to an remote API (CURL), so I was hoping to save on API calls by only doing it the first time and then storing the results in my session variable.
GeoIP.class.php:
    

require_once('geoPlugin.class.php');

class GeoIP 
{
    public $currentIP;
    public $geoplugin;

    function __construct($forceIP = null){
        if(!empty($forceIP)) $this->currentIP = $forceIP;
        else $this->currentIP = $_SERVER['REMOTE_ADDR'];

        $this->geoplugin = new geoPlugin();
        $this->geoplugin->locate($forceIP);
    }

    function isValid(){
        return !empty($this->geoplugin->countryName);   
    }

    function getCountry(){
        return  $this->geoplugin->countryName;
    }

    function getRegion(){
        return  $this->geoplugin->region;
    }

    function getCity(){
        return  $this->geoplugin->city;     
    }

    function getPostalCode(){
        return $this->geoplugin->postalCode;    
    }

}

geoPlugin.class.php:
<?php
/*
This PHP class is free software: you can redistribute it and/or modify
the code under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version. 

However, the license header, copyright and author credits 
must not be modified in any form and always be displayed.

This class is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

@author geoPlugin (gp_support@geoplugin.com)
@copyright Copyright geoPlugin (gp_support@geoplugin.com)
$version 1.01

This PHP class uses the PHP Webservice of http://www.geoplugin.com/ to geolocate IP addresses

Geographical location of the IP address (visitor) and locate currency (symbol, code and exchange rate) are returned.

See http://www.geoplugin.com/webservices/php for more specific details of this free service

*/

class geoPlugin {

    //the geoPlugin server
    var $host = 'http://www.geoplugin.net/php.gp?ip={IP}&base_currency={CURRENCY}';
    var $postalHost = 'http://www.geoplugin.net/extras/postalcode.gp?lat={LAT}&long={LONG}';

    //the default base currency
    var $currency = 'USD';

    //initiate the geoPlugin vars
    var $ip = null;
    var $city = null;
    var $region = null;
    var $areaCode = null;
    var $dmaCode = null;
    var $countryCode = null;
    var $countryName = null;
    var $continentCode = null;
    var $latitute = null;
    var $longitude = null;
    var $currencyCode = null;
    var $currencySymbol = null;
    var $currencyConverter = null;
    var $postalCode = null;

    function geoPlugin() {

    }

    function locate($ip = null) {

        global $_SERVER;

        if ( is_null( $ip ) ) {
            $ip = $_SERVER['REMOTE_ADDR'];
        }

        $host = str_replace( '{IP}', $ip, $this->host );
        $host = str_replace( '{CURRENCY}', $this->currency, $host );

        $data = array();

        $response = $this->fetch($host);

        $data = unserialize($response);

        //set the geoPlugin vars
        $this->ip = $ip;
        $this->city = $data['geoplugin_city'];
        $this->region = $data['geoplugin_region'];
        $this->areaCode = $data['geoplugin_areaCode'];
        $this->dmaCode = $data['geoplugin_dmaCode'];
        $this->countryCode = $data['geoplugin_countryCode'];
        $this->countryName = $data['geoplugin_countryName'];
        $this->continentCode = $data['geoplugin_continentCode'];
        $this->latitude = $data['geoplugin_latitude'];
        $this->longitude = $data['geoplugin_longitude'];
        $this->currencyCode = $data['geoplugin_currencyCode'];
        $this->currencySymbol = $data['geoplugin_currencySymbol'];
        $this->currencyConverter = $data['geoplugin_currencyConverter'];

        if(!empty($this->latitude) && !empty($this->longitude)){
            $host = str_replace( '{LAT}', $this->latitude, $this->postalHost );
            $host = str_replace( '{LONG}', $this->longitude, $host );
            $data = array();
            $response = $this->fetch($host);
            $data = unserialize($response);

            $this->postalCode = $data['geoplugin_postCode'];
        }

    }

    function fetch($host) {

        if ( function_exists('curl_init') ) {

            //use cURL to fetch data
            $ch = curl_init();
            curl_setopt($ch, CURLOPT_URL, $host);
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
            curl_setopt($ch, CURLOPT_USERAGENT, 'geoPlugin PHP Class v1.0');
            $response = curl_exec($ch);
            curl_close ($ch);

        } else if ( ini_get('allow_url_fopen') ) {

            //fall back to fopen()
            $response = file_get_contents($host, 'r');

        } else {

            trigger_error ('geoPlugin class Error: Cannot retrieve data. Either compile PHP with cURL support or enable allow_url_fopen in php.ini ', E_USER_ERROR);
            return;

        }

        return $response;
    }

    function convert($amount, $float=2, $symbol=true) {

        //easily convert amounts to geolocated currency.
        if ( !is_numeric($this->currencyConverter) || $this->currencyConverter == 0 ) {
            trigger_error('geoPlugin class Notice: currencyConverter has no value.', E_USER_NOTICE);
            return $amount;
        }
        if ( !is_numeric($amount) ) {
            trigger_error ('geoPlugin class Warning: The amount passed to geoPlugin::convert is not numeric.', E_USER_WARNING);
            return $amount;
        }
        if ( $symbol === true ) {
            return $this->currencySymbol . round( ($amount * $this->currencyConverter), $float );
        } else {
            return round( ($amount * $this->currencyConverter), $float );
        }
    }

    function nearby($radius=10, $limit=null) {

        if ( !is_numeric($this->latitude) || !is_numeric($this->longitude) ) {
            trigger_error ('geoPlugin class Warning: Incorrect latitude or longitude values.', E_USER_NOTICE);
            return array( array() );
        }

        $host = "http://www.geoplugin.net/extras/nearby.gp?lat=" . $this->latitude . "&long=" . $this->longitude . "&radius={$radius}";

        if ( is_numeric($limit) )
            $host .= "&limit={$limit}";

        return unserialize( $this->fetch($host) );

    }

}

My caller:
if(isset($_GET['forceIP'])){ //overwrite the IP address
    $myGeo = new GeoIP($_GET['forceIP']);
}
else{
    if(empty($_SESSION['directory']['geoip'])){
        $myGeo = new GeoIP();
        $_SESSION['directory']['geoip'] = $myGeo;
    }
    else{
        $myGeo = $_SESSION['directory']['geoip'];
    }
}

A:

The answer is no, as the object is not being reconstructed.  What is called however are the magic __sleep() and __wakeup() methods, the first when you store it to $_SESSION and the second when you retrieve it.
You should take a quick look at this thread to make sure you've considered some of the problems of using $_SESSION to store objects.

