February 2013
Intermediate to advanced
538 pages
20h 55m
English
Content preview from Programming PHP, 3rd EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Serialization
Serializing an object means converting it to a bytestream
representation that can be stored in a file. This is useful for persistent
data; for example, PHP sessions automatically save and restore objects.
Serialization in PHP is mostly automatic—it requires little extra work
from you, beyond calling the serialize() and unserialize() functions:
$encoded = serialize(something); $something = unserialize(encoded);
Serialization is most commonly used with PHP’s sessions, which
handle the serialization for you. All you need to do is tell PHP which
variables to keep track of, and they’re automatically preserved between
visits to pages on your site. However, sessions are not the only use of
serialization—if you want to implement your own form of persistent
objects, serialize() and unserialize() are a natural choice.
An object’s class must be defined before unserialization can occur.
Attempting to unserialize an object whose class is not yet defined puts
the object into stdClass, which renders
it almost useless. One practical consequence of this is that if you use
PHP sessions to automatically serialize and unserialize objects, you must
include the file containing the object’s class definition in every page on
your site. For example, your pages might start like this:
include"object_definitions.php";// load object definitionssession_start();// load persistent variables?><html>...
PHP has two hooks for objects during the serialization and
unserialization process: __sleep()
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.