PHP and tips

PHP bitwise operators

2010-05-13T15:31:00.000-07:00

Bitwise operator, class flags and constant with PHP

zend cache

2010-04-24T04:56:00.001-07:00

zend cache overview

Site moved

2010-04-22T14:05:00.000-07:00

I've decided to move my blog to another my domain (hosted by dreamhost), mainly because of the time wasted to format the text in my posts (very poor editor) and impossibility of uploading files.Ufortunately it's not been possible to move the "google followers" to the new site (google limitation), so I've had to make another widget. If you keep following this blog, please join the new site (box

Custom rules for zend standard rewrite router

2010-04-20T15:37:00.000-07:00

In this post, an overview of Zend routing [official doc] and how set custom rule for routing (tested on Zend v1.10). Routing is basically how zend associate URLs tothe controllers, actions and parameters of the application (similar to apache mod_rewrite but PHP based therefore much more powerful). Default routing As it is known, the default Zend routing uses the following schema: [

Inside wordpress: notes about common variables and functions to add extra features

2010-04-20T14:13:00.000-07:00

I've recently used wordpress to make some simple web sites. Wordpress is a very fast solution when creating a blog or a site of which the requirements are just a subset of the wordpress features.What we can do with wordpress: fixed pages, site news (that are blog posts), simple search, multi-level page and news content management, WYSIWYG editor, changeable themes, lots of free themes already

sessions vs cookies with load balancer

2010-04-15T14:05:00.000-07:00

It's a well known fact that HTTP is a stateless protocol and cookies are needed to keep the communication session.When dealing with sessions with PHP, we have two main solutions:- set manual cookiesOne approach is using directly the PHP functions to set the cookies. When possible I don't use manual cookies(except than keeping an hash string for the user identity or keep the session after the

Singleton is bad !!

2010-02-28T11:02:00.000-08:00

An interesting suggestion emerged from some speakers (1 and 2) of the last PHP UK conf is: do not use the Singleton design pattern !!At the beginning it made me a little astonished as it's one of the most widely used design patterns, in addition ZF and lots of other projects use it. However, after a while I agreed the idea. Singleton actually had created some problems when I had to do some class

PHP UK conference 2010 talks

2010-02-28T04:31:00.000-08:00

I attended the PHP UK conference 2010 on Friday. Unfortunately the event took place in one day, so there were three talks at each time slot in different rooms. I had to choice the most promising each time. It was a pity to have some very interesting ones at the same time (like AntiPHPatterns and RDBMS, or DB optimisation and the PHP 5.3). Fortunately, I've already found almost all the slides

PHP UK 2009 conference - talk slides

2010-02-27T10:09:00.000-08:00

I've just searched and found the slides of the online talks made at the PHP conference 2009 that I couldn't attend.For some of them, a few-line-summary.The future's so bright, I gotta wear shades (keynote) by Aral Balkannot found :(Clouds on the horizon? Get ready for Drizzle by David AxmarkslidesDrizzle, a light faster version of mysql: only UTF8, features as plugin, semplified protocol. BSD

Upload a tree of files and subdirectory to a remote FTP server

2010-02-14T05:27:00.000-08:00

I've recently been asked to move a site (1Gb of files) from a Italian hosting linux (no ssh) to the same cheap hosting but to another server windows (damn ! no ssh, no console commands from PHP, the only way to upload files is the old slow uncool FTP).Problem: I've got an extremely poor upload bandwith in my house in UK. So, I've used another hosting with SSH (dreamhost, in US) and:1) got data

practice tests for zend php 5 certfication

2010-02-05T13:29:00.000-08:00

I'm selling4 exam practice online test for "Zend PHP 5 Certification", GBP 10.descriptionhttp://shop.zend.com/eu/php-certification/zend-php-certification-online-practice-testing.htmlcontact me at elvisciotti [at] gmail (dot) com, payment through paypal

PHP and scalability

2010-02-04T14:59:00.000-08:00

As PHP is becoming a widely used web server technology, more and more developers are comparing PHP with other technologies like J2EE or .NET.It has been the butt of criticism as considered not scalable: totally wrong !A system is scalable when is able to keep the performances under an increased load, mainly due to more users. Speaking about scripting execution velocity (that is a constant in

Who reads this blog ?

2010-01-30T10:27:00.001-08:00

This is the map made by google analytics on this blog.It's rather foreseeable to see which are the countries more interested in a technical blog.I'm only surprised to see no visits from China and Norway, as well as same number of visitors from Spain and Ukraine and Romania.To obtain a better paid job I'm really thinking about moving to Madagascar :D

PHP for file moving / managing

2010-01-30T03:57:00.000-08:00

PHP is a technology damned cool for web application but the language doesn't provide an advanced syntax as Python in itself. However, by writing readable and maintenable code (for instance by smartly separating features in function and classes), PHP is satisfying also to make file managing / system scripts, IMHO of course :)ExampleHere is a simple script I'm using to copy the latest mp3 files

Simple PHP script to edit front end components

2010-01-26T04:31:00.000-08:00

I've recently built a very simple web site. The only dynamic requirement was having some parts of the front end editable (WYSIWYG) by an administration area (user and password). Basically, a very simple basic CMS for one user.SolutionA MySQL database is not needed, saving to files is much more appropriate for these requirements. Also SQLite is not necessary, as we just want to do only basic

My Zend Certification

2010-01-20T04:35:00.000-08:00

Just passed my ZCE PHP5!!90 tech questions, some of them answerable only by reading some books, some others by knowing the exact behaviour and arguments of PHP5 functions and settings (quite a lot of stuff to remember considering also XML, PDO, STD lib,streams and filters), some other only with work experience, some of them with a code/algorithm comprehension ability and deep OOP skills.It will

PDO example

2010-01-14T07:44:00.000-08:00

try {$pdo = new PDO("mysql:host=127.0.0.1;dbname=dev;","root","" );#$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);$pdo->exec("DELETE FROM `User` WHERE id<>293968 ");#insert$insertedRows = $pdo->exec("INSERT INTO `User` (username, password) VALUES ('elvis','ciotti') ");$lastInsertId = $pdo->lastInsertId();echo "Inserted $insertedRows rows [id = $lastInsertId]\n";$pdo->exec("DELETE

PHP Arrays sort

2009-12-19T14:34:00.000-08:00

There are lots of PHP defined function to order arrays (the core of PHP, technically are hashmaps), ordering by value or keys, preserving key order or not, using an user-defined function, normal or reverse order, etc... Following, some clear example of the main ones, and some tips about how to remember themORDER BY VALUE sort(): order by VALUE (keys destroyed and renumberted starting from

Netbeans 6.8

2009-12-10T14:06:00.000-08:00

Netbeans 6.8 is now available !New features:Symfony support (integrated prompt, syntax + help for command line code generator, shortucts) + YAML syntax supportbetter code completion, supporting PHP 5.3 features (namespaces)PHPUnit improvementsPHP application from remote serversSQL better auto completitionEmbedded Browser + Web Preview for HTML and CSS

Checking PHP script performance with Xdebug

2009-11-26T13:39:00.000-08:00

Xdebug [http://www.xdebug.org/] is a useful tool to debug PHP scripts. An interesting feature is the script profiling. If the option is enabled, Xdebug will be able to trace and save information (time, details) about all the functions/methods called in the script (CLI or Apache). The aim of the profiling is mainly recognizing bottlenecks or simply what parts of the code that are slow. In order

Profiling MySQL

2009-11-19T15:08:00.000-08:00

To analyze the db server usage in a complex PHP application, the first step is to profile the db server.There are lots of tools to profile, but I think it's very easy to make a customized code to save the data really needed.The idea is save information about some queries in the production environment (about 1% of the queries is usually enough, depending on the traffic).MySQL profilingHoping

Simple effective PHP debugging + backtracking

2009-11-19T14:49:00.001-08:00

During PHP debugging I often need to debug complex data. Is not always possibile to use Xdebug and the IDE debugging features with MVC frameworks, and also some arrays/object are too big and unhandy for FirePHP.A valid solution might be a traditional "print_r"/"var_dump" + "exit"Two problems:1) accidental commits to the staging/production environment.2) it takes time to understand where they are

MySQL dump importing

2009-11-19T14:46:00.000-08:00

Today I realized that "mysqlimport" is not working as expected on Wamp environment.A working way to import a sql/dump file is to use the "mysql" executable#localhostmysql --u root -p --user=root --force [DBNAME] < [FILE.SQL]

PHP 5.3

2009-11-16T16:08:00.000-08:00

I've just read this pdf from I.A.'s blog about PHP 5.3 performances.My comments:PerformancesWhat I really consider good is the performance increasing (5/10%) that include a smarter behaviour with require/inclusion, smaller binary size and better stack performance.Features- Namespaces are OK, but not really necessary. A good code can be written also without them.- I think the best feature is the

How to optimize PHP applications

2009-11-03T15:58:00.000-08:00

There are lots of advices on the web about how to speed up PHP applications.The best reading I've found are written by Ilia Alshanetsky [blog]:PHP & PERFORMANCE [pdf]By: Ilia AlshanetskyCommon Optimization Mistakes [pdf]PHP Quebec 2009Enjoy !

a Javascript function to manage function timeout

2009-10-15T13:35:00.000-07:00

Today I worked with form validations and AJAX requests associated with the event keyup in the input fields.Sometimes the validation requires an AJAX call (for instance to check if the typed text already exists in the DB). In order to avoid a request for each char typed, a good solution might be using set/clearTimeout.With the aim of doing only one function to manage all the timeouts of the

printing the backtrace in a complex PHP application

2009-10-12T13:41:00.000-07:00

the PHP debug_backtrace [man] function is very useful to understand where a function/method is called.It prints the back trace of the code.Example: In the framework I'm currently using there are ORM classes to access the DB. So, it takes long to understand where the query is launched when needed. Solution: save in a global variable (or in a field of the class) the list of the queries launched and

How to search complex source code using regular expressions

2009-10-12T13:38:00.000-07:00

Today I needed to search the source code that ware calling a function with a complex array of parametersURL::Make( 'site/store.inc.php', array( 'action'=>'view','id'=> [... STH...] ,'idTwo'=> [... STH...] ) );Considering this requirements:- there are lots of similar function (to exclude from the search) with an argument less or an argument more- there may are additional spaces in the line- some

An idea for DB server load balancing

2009-10-12T12:38:00.000-07:00

If the application has a heavy load of reading queries and there are no problems with the application requirements,a simple possible idea to balance the db server loading is to run the INSERT/UPDATE/ALTER queries in all the servers and run the SELECT queries in just one server (chosen randomly).Have a look at the 'loadBalancedQuery' function: if the query modifies the db it will be executed in

UTF8 in LAMP applications: overview and how to solve the common issues

2009-10-11T05:33:00.000-07:00

The problemIn a LAMP application the text is frequently saved/retrieved from/to a database and files. We must consider all the different encoding (mapping characher-byte value): latin1 iso8859-1, latin9, UTF-8 (utf8) etc...Lots of applications use ISO8859 encoding and some PHP functions to convert the characters (htmlentities, htmlspecialchars etc...)The solutionConverting all the text from an

Mass rows copying (duplicating) with filed customization - MySQL

2009-09-28T15:35:00.001-07:00

Let's suppose we have a table with the following structure and data:# `table`id | a | b | c |---------------------------1 | "aaa" | "xxx" | "ccc"2 | "aab" | "yyy" | "ccc"3 | "aba" | "yyy" | "ccc"4 | "abc" | "xxx" | "ccc"5 | "dcz" | "xxx" | "eee" Now, we want to copy some records (only some columns) to the same table AND change some of them with a fixed value.Requirements:

How to recursively check syntax of PHP files

2009-09-15T09:38:00.000-07:00

The executable of PHP supports the '-l' option, that checks the syntax instead of parsing the file.Using the command 'find', it's possibile to do a interesting operation: syntax checking of all the files recursively, to avoid parse errors in some script !!find ./ -type f -name \*.php -exec php -l {} \; ";the result will be a list of files, example:No syntax errors detected in ./codebase/

help of useful commands

2009-08-30T14:07:00.000-07:00

In this post, just a link of files contains help guide ([command] --help) for the most common unix shell commands.cpfindgrepgunzipgziphelplsmvpstarwget

Monitor linux web-servers with monit

2009-08-23T03:45:00.000-07:00

"monit is a utility for managing and monitoring processes, files, directories and devices on a Unix system. Monit conducts automatic maintenance and repair and can execute meaningful causal actions in error situations. E.g. monit can start a process if it does not run, restart a process if it does not respond and stop a process if it uses to much resources. You may use monit to monitor files,

Compare Files between two directories recursively - PHP script

2009-08-22T10:24:00.000-07:00

In this post I'll present my PHP class to show differences (file missing or different file date) between files in two directories (recursively).It's useful to compare two websites (Example, test and live versioning the same server) and show the differences, much faster than a FTP synchronization, and customizable (size differences instead of time, PHP copy commands with backup etc...).Example of

benchmark: boolean variables value check

2009-07-21T14:00:00.000-07:00

$a = NULL;$t = microtime(true);for($i = 0; $i<10000000; $i++) { if ($a) {} }print microtime(true)-$t."\n"; //2.84 sec$t = microtime(true);for($i = 0; $i<10000000; $i++) { if ($a==true) {} }print microtime(true)-$t."\n"; //3.52sec$t = microtime(true);for($i = 0; $i<10000000; $i++) { if ($a===true) {} }print microtime(true)-$t."\n"; //3.0 sec$t = microtime(true);for($i = 0;

benchmark: array_key_exists vs isset

2009-07-21T13:15:00.000-07:00

When the aim is to check if the element exists in an array and has a value not null, better to use isset(array[index]), that is much faster than array_key_exists(index, array).#PHP 5.3.0 command line - Amd turion 64 1.6 Ghz#create array$a = array();for($i = 0; $i<100000; $i++) { $a[] = "$i asd a".($i*2)." sd";}#isset$t = microtime(true);for($i = 0; $i<10000000; $i++) { isset($a[$i]);}

Functional testing for web applications: Selenium IDE for firefox

2009-07-18T11:10:00.000-07:00

In a previous post I wrote about PHP Unit testing.In software science, the levels above Unit testing are Integration, System and System integration testing.For a standard web application I suggest to use only Selenium [official site], a powerful complete framework , distributed with apache licence 2.0 (a free-software, GPL compatible).Selenium includes many components. In my opinion the most

How to solve SVN conflicts. Netbeans SVN plugin tools

2009-07-09T11:21:00.000-07:00

SVN [official site] is the most powerful open source version control software at the moment.Introduction (for who doesn't know it at all)Basically, SVN is a server/client system. The server that contains the repository (source code of our application).The clients get the source code (CHECK OUT) or only the new files (UPDATE) from the server. The opposite operation is called COMMIT, and consists

SVN to FTP/web on Windows with svn client+winscp

2009-07-09T11:20:00.001-07:00

Post moved to the new blog: Svn to ftpHow to deploy a web application and to quickly deploy future updates/patches from a SVN repository into a remote web server (only with ftp access and without possibility to setup svn client) ?Here are my suggested steps:export SVN (that is obtain the last repository without ".svn" directories)process the exported SVN (e.g. adding or deleting files before

Unit testing: a brief introduction to PHPUnit

2009-07-06T11:13:00.000-07:00

Every software needs testing [wiki], starting with testing software units [wiki] (the smallest parts of a software, that are functions and classes).Briefly, a test is a code which runs and ensure that our code behaves as expected. Here is an example of a test to check a mail validator function:print ( validateEmail("test@site.com") && !validateEmail("test@site") && !validateEmail("@site") && !

PHP 5.3.0 released

2009-07-01T13:58:00.000-07:00

I don't like writing posts for every new PHP release as other PHP blogs, but this time it's worth doing it !PHP 5.3 implements important new OOP features:namespaceslate static binding and __callStatic() !anonymous functionsPhar extension (pratically, it's the same as JAR for java files)Forother improvments and bug fixing, see change log

Debugging techniques with free tools [updated 30 June]

2009-06-27T04:50:00.000-07:00

Netbeans PHP 6.* + Xdebug + Firefox (with netbeans extension to server debug with javascript) !howto configure with Wamp 2.0h:- download php_xdebug-2.0.4-5.2.8.dll into the Wamp folder- open port 9000 in the firewall- edit php.ini adding[xdebug]zend_extension_ts="c:/wamp/bin/php/php5.2.9-2/ext/php_xdebug-2.0.4-5.2.8.dll"xdebug.remote_enable=onxdebug.remote_handler=dbgpxdebug.remote_host=

Symfony: password hashing and login

2009-06-23T04:38:00.000-07:00

It's a good practice not to keep the clear values of the passwords in the db, but to store only their hash values.You can do login operations comparing the hash value of the inserted password with the stored hash value.How to do it with Symfony 1.2, propel ORM, MD5 hashing:db schema: Use a VARCHAR, length must be at least 32 validator:- require a minimum length (ex: 3 chars) or (better) regexp

LAMP documentation links

2009-06-22T11:34:00.000-07:00

PHPOnline http://www.php.net/manual/en/Offline CHM http://uk2.php.net/get/php_manual_en.chm/from/a/mirrorpear packages http://pear.php.net/manual/en/packages.phpSYMFONY v1.2book (the definitive guide) : online html | PDF versionJobeet tutorial - propel: online html | PDF versionForms: online html | PDF versionCookbook: online html | PDF versionAPI online http://www.symfony-project.org/api/1_2/

JSON generation with PHP and parsing with jQuery

2009-06-14T14:52:00.000-07:00

JSON [official site][wiki] is a data interchange format (similar to XML, but simpler), often used for WEB 2.0 applications to load structured data with AJAX HTTP calls.- PHP offers functions to encode and decode JSON from/to a PHP value.- jQuery includes a function (getJSON) to parse HTTP resource with JSON data.JSON pseudo grammar#json block: comma separated couple key: valueJSON_BLOCK = { KEY1:

MySQL : version differences notes (draft)

2009-06-10T01:41:00.000-07:00

Relevant features added in Mysql 4.0FULLTEXT searchINNODB tables (and on [delete|update features]UNION statementTRUNCATE TABLE statementmultiple table delete and updateRelevant features added in Mysql 4.1Subquery (nested query) supported"CREATE table LIKE table 2" syntax supportedadded storages:- EXAMPLE (for developers)- NBCLUSTER (table partitioned over many computers)- CSV (comma separated

INNODB storage engine: notes

2009-06-08T12:25:00.000-07:00

Advantagestransactionsrow-level lockingforeign key constraints ! and behaviourON [DELETE|UPDATE] [RESTRICT|CASCADE|SET NULL|NO ACTION|SET DEFAULT]DisadvantagesINNODB does NOT support FULLTEXT index (MyISAM does)not initial value for auto_increment keys

array_walk example

2009-06-08T09:20:00.000-07:00

bool array_walk ( array &$array , callback $funcname [, mixed $userdata ] )/* example !! * transform array with other arrays as elements into an array with simple elements * array trasform ! */$ar = array( array(1,2), array(10,20), array(100,200) );function sum(&$ar) //NOTE: Argument By reference{ $ar = $ar[0]+$ar[1];}array_walk($ar, "sum");print_r($ar);/*Array( [0] => 3 [1] => 30

PHP security: input validation and XSS

2009-06-08T06:07:00.000-07:00

for lots of reasons, security included, it's very important to validate all user input and protect our application from intentional or accidental wrong inputs.First of all, here are some advicesdon't use register_globals ! A malicious user may change value of script variables simply modifying the query stringdon't use $_REQUEST: possibile loss of data. Use $_GET and $_POSTNumber validationuse

Design Pattern: Strategy

2009-06-08T03:11:00.000-07:00

Strategy is a way to encapsulate, manage and interchange (also at runtime) algorithms.In the following example, we have three classes (A,B and C) that implement an interface with the method f().The class AlgoContainer must be initiated by passing the object (external instantiation) or the class name (internal instantation).Interface StrategyInt{ public function f();}class A implements

Design Pattern: Decorator

2009-06-08T02:48:00.000-07:00

Decorator is similar to Proxy.Basically, decorator is an extension (or wrapper) of the original class (component) and adds features.A decorator contains a pointer to the component class (initialized by the constructor), and the methods of the component overridden.Example:class ImgComponent {private $src;private $alt;public function __construct($name, $src) { /* assign to properties*/ };public

Design Pattern: Adapter

2009-06-08T01:56:00.000-07:00

The Adapter design pattern is basically a wrapper, that is a class which provides methods to access to another class.It's commonly used to normalize incompatibile interfaces.It's similar to Proxy pattern, but it's a little different. Proxy includes an object and controls accesses to it; Adapter provides an interface to the object, usually by inheritance.class A {public static function sort(array

Design Pattern: Observer

2009-06-07T13:44:00.000-07:00

The behavioural design pattern Observer allows to automatically update one-to-many dependences.Structure: an object (Hence: $subject) contains a list of observer references, and provides a method notify() that invoke update() of every observer. Also observers have a reference to $subject, used inside update().Commonly used to event handling (listeners) and login issues.Implementation in PHP5:

Design Pattern: Proxy

2009-06-07T13:17:00.000-07:00

It provides a filtered controlled access to an object, without exposing it directly.How to implement in PHP5:Declare a class:constructor: instantiates the object (only the first time) and keeps the instance into a private properties- implement the methods that provide a controlled access to the internal objector- use the magic method __call($name, $value), then checks/filters the name and

Design Pattern: Factory

2009-06-07T12:32:00.000-07:00

Factory is a creational design pattern which handles object creation.A factory class provides the methods to create object (whit a superclass in common), but let subclasses to decide which class will be instantiated.Basically, it contains a static method ("connect" in the example below) that accept one parameter and makes a switch on it. Depending on the parameter, a new object of different type

Design Pattern: Value

2009-06-07T07:51:00.000-07:00

Consider a class Val which contains a value, and a method add() which add another value with the same type.class Val { private $value; public function __construct($value=0) {$this->value = $value; } public function get() { return $this->value; } public function add($newVal) { //(1) WRONG: //$this->addV += $value; //WRONG !! // (2) RIGHT !! return new

Design Pattern Singleton

2009-06-07T07:27:00.000-07:00

Singleton is a creational pattern which ensures a class has only one instance, and provide a global pointer to access it.The most common example is a database connection.The idea: the class doesn't provide a constructor, but a method to return an instance. That instance is assigned to a static properties and is instantiated only at the 1st access.class Example{ // Hold an instance of the class

XMLWriter

2009-06-07T05:47:00.000-07:00

the PHP5 XMLWriter class allows to easily create XML well-formed documents.The most useful methods:openURI($output) // use 'php://output' as argument to stream directlystartDocument('1.0') // add the initial tag. 1st argument : xml versionwriteElement('hr') // write the empty node [hr/]writeAttribute('src','img.gif') //write the attribute (inside the last node) and valuee.g: [img src="http://

SPL: DirectoryIterator

2009-06-07T05:14:00.000-07:00

foreach (new DirectoryIterator('.') as $fileInfo) { //if($fileInfo->isDot()) continue; echo "Name: ".$fileInfo->getFilename() . "\n"; echo "Last : ".date("d/m/Y H:i", $fileInfo->getCTime()) . "\n"; echo "Size: ".$fileInfo->getSize() . " byte\n"; echo "Type: ".$fileInfo->getType() . "\n"; //dir or file echo "Executable: ".($fileInfo->isExecutable()?"yes":"no") . "\n"; echo "

ArrayAccess: use object as an array, file manager example

2009-06-06T09:59:00.000-07:00

ArrayAccess (PHP5) allows to treat objects as an array.View below the interface scheme, with explanatory commentsArrayAccess { //PHP5 built-in Interface// returns true/false if the element in the position $offset exists/doesn't existabstract public boolean offsetExists ( string $offset ) // returns the element at the position $offsetabstract public mixed offsetGet ( string $offset )// set the

References are not pointer in PHP5 !

2009-06-06T08:18:00.000-07:00

Exceptions in PHP5

2009-06-06T07:08:00.000-07:00

PHP5 supports Exception model, like C++/C# and Java.syntax to catch exception:try {//code which can launch an exception// [...]// manual exception throwthrow new Exception("thrown exception");//not executed ! (throw command is caught belowprint "not printed!";}catch(Exception $e) { print $e->getMessage();}this code prints : "thrown exception".It's possibile to throw an exception inside a catch

PHP5 Namespaces

2009-06-06T05:00:00.000-07:00

Namespaces are available in PHP as of PHP 5.3.0A namespace is a container with classes, function and constants (also available in PHP>5.3.0), similar to the namespaces in C++/C# and packages in Java. As indicated in the official PHP documentation, namespaces help us to solve name collisions and use alias to call long name classes/functions.definition syntax:

Late static Bindings (PHP >= 5.3.0)

2009-06-06T03:25:00.000-07:00

in programming languages, binding is the association of the values with the identifiers.association before running: early bindingassociation at runtime: late binding (also called virtual or dynamic)PHP5 supports the classic late binding. At runtime, PHP5 distinguishes the superclass from the subclasses object, respecting the overridden methods rules.The late binding for static methods are

Object references, assignment and as function arguments

2009-06-05T17:24:00.000-07:00

As of PHP5, objects are treated REFERENCE ! (same behaviour as C++ and Java)1) assignment from an objects to another copies the reference, not the content !!What is a reference ? it's a variabile/object that ONLY contains the pointer to the effective object in the memory. As I said in a previous post, the assigment instruction copy ONLY the value (pointer) of the object-pointer, it doesn't

Obtain information about a class

2009-06-05T13:13:00.000-07:00

PHP5 includes interesting APIs to obtain information (list of members and methods) about the internal classes or interfaces.Example of PHP5 interesting classes/interfaces: Exception, Iterator.To obtain information about a class, instantiate the class ReflectionClass passing the name of the class we want information about. Now pass that instance to the static method export() of the class

the "==" and the "===" operators

2009-06-05T09:03:00.000-07:00

PHP has two types of comparison operators: "==" and "===" ( and respectively "!=" and "!==" ).Variables"==" offers a simple comparison of the content of variables, skipping the type (int, string, boolean,...) of the variables.The following expression are equivalent to the operator "==":false 0 "" '' "0" 0.0 -0 !1 array() $i // where $i is not initialized (notice generated) strpos("abcd","a") // (

final keyword in PHP5

2009-06-05T07:51:00.000-07:00

Likewise Java, the meaning of the keyword "final" in php5 is:final classes: not extendablefinal class A { ...} final methods: not overridableclass A { final public function f() { ... } ...} final class members(properties): not supported in PHP5 !! (differently from Java)

serialize, unserialize, __sleep() and wakeup()

2009-06-05T02:44:00.000-07:00

definitions:Serialization: convert an object into a string (storable representation). The included object (instantiated and assigned to internal members) are included in the string.Unserialization: convert the string into the original objectPossibile uses: shopping cart serialize (to use after or to save into a db), user session save, object transfer between different applications.serialize($

Object iteration 2/2

2009-06-05T01:36:00.000-07:00

about object iteration, in php5 it's possibile to use Iterators (similar to Java and C++).Iterator is a PHP5 default interface that includes the public methods (to implement):mixed current ( ) // returns the current element in the loop ($key)scalar key ( ) // returns the current key in the loop ($val)void next ( ) // called for obtain the next elementvoid rewind ( ) //

Object iteration 1/2

2009-06-05T01:21:00.000-07:00

the construct foreach in PHP5 supports also object, in addition to arrays.foreach($object as $key=>$val){//$key will be equal to the nth member name//$val will be equal to the nth member value}Which members are visibile ? it depends on the "foreach" position !inside the class ($this is the object): all the members are visibileoutside the class: only public members are visibleinside an inherited

"Overloading" in PHP5 and magic methods

2009-06-04T11:29:00.000-07:00

PHP doesn't support constructor / methods overloading with the classical syntax !"Overloading" in PHP5 is realized via the magic method __call($functionName, $argumentsArray)Dynamic creation of PROPERTIESLet's consider a class X (without content) and one its instanceclass X {}$x = new X();Now, If we try to read the inexistent property "m1" of the class, that is:print $->m1;we haveif the class X

polymorphism in PHP5

2009-06-04T10:58:00.000-07:00

polymorphism in PHP5 sample class superclass{ public function f() { print "superclass-method\n"; }}class subclass extends superclass{ //override public function f() { print "subclass-method\n"; } public function added() { print "subclass-added-method\n"; }}function callF( $obj) //superclass{ $obj->f(); if ($obj instanceof subclass) $obj->added();}callf(new superclass()); //

Implementing multiple interfaces in PHP5 and instanceof operator

2009-06-04T10:00:00.000-07:00

//interfacesinterface Intf{public function f(); }interface Intg{public function g();//public function f(); // error in case of multiple implementing (with Intf) }//simple implementationclass Cf implements Intf{public function f(){ print "interface Cf, function f"; } }//multiple implementationclass Cfg implements Intf, Intg{public function f(){ print "interface Cfg, function f"; }public function g

PHP5: inheritance and overriding

2009-06-04T08:45:00.000-07:00

example of inheritancefigure -> rectangle -> square figure -> triangleoverriding:methods overriding: "rectangle" and "triangle" override getArea() method (declared in the superclass abstract "figure")to override a method you MUST declare it with the same signature (name + number + arguments sequence)superclass method calling: figure declare a method to get area and a contructor, overridden in the

Static members and methods in PHP5

2009-06-04T06:38:00.000-07:00

PHP5 supports "static" features, in according to OOP principles.Note: visibility (private, protected, public) rules for static properties/methods are THE SAME AS common ones.----------------------------------------------------Static properties and methods of a class:don't need an instance of the class to use themcallable specyfing classname, followed by "::" and the property name (including the

PHP5: object references, object cloning and __clone()

2009-06-04T06:12:00.000-07:00

Let's make a simple class with a value (default=1), set and get methodsclass Obj{private $var=1;public function setVal($var) { $this->var = $var; }public function getVal() { return $this->var; } }Following, another class that includes the previous one (Or better, it includes a reference to the previous class, and the object will be instantiated by the constructor)class A{private $obj; //

passing parameters to function: PHP4 and PHP5

2009-06-04T03:57:00.000-07:00

VariablesIn PHP4 and PHP5, variables by default are passed by value (copy) to functions. It means that outside the function the variables don't change$v = 1;function increment($v) { $v++; }increment($v);print $v; // 1 !!If you want to pass by reference, use the operator &$v = 1;function increment(&$v) { $v++; }increment($v);print $v; // 2 !!Objectsby default:PHP4: object passed by valueinside

abstract classes in php5

2009-06-04T03:24:00.000-07:00

abstract class:you CANNOT instantiate it, you can ONLY INHERIT it !some methods (at least one) are abstract and the subclass which inherit from it must implement its abstract methods (same visibility, name and arguments)note: the subclass can access all the protected (and public) methods and members (NOT the private ones) of the superclass !simple explanatory example://abstractabstract class

php5 interfaces

2009-06-04T02:48:00.000-07:00

PHP5 supports "interfaces".What is an interface ? Basically, it's a definition of a class type with methods. If you implement an interface, you must write all the methods in that interface.Example:Let's suppose there is a "dbConnection" interface, that contains all the methods to db access.Interface dbConnection{public function __construct($host, $user, $pass, $db);public function query($q);