Singleton Pattern

This pattern is probably one of the most simple and used pattern.

As php manual says: The Singleton pattern applies to situations in which there needs to be a single instance of a class. The most common example of this is a database connection. Implementing this pattern allows a programmer to make this single instance easily accessible by many other objects.

There are tons of information about this pattern over the Internet so I let you google for it.

You can find a singleton implementation in Simple MVC framework example.

How to create a command (task) in Symfony 2

This tutorial is deprecated. It was written when Symfony2 was in beta. 

In Symfony 1.x a task is a command line tool to help perform tasks around the application. The same is in Symfony 2. Unfortunately in Symfony2 there is no tool to auto-generate some code for these. To create a Symfony2 Command you must to have or to create in your Bundle a folder named Command. Here, you must create a file named MytaskCommand.php with the following code:

 

<?php
namespace ApplicationVremeaBundleCommand;

use SymfonyBundleFrameworkBundleCommandCommand;
use SymfonyComponentConsoleInputInputDefinition;
use SymfonyComponentConsoleInputInputOption;
use SymfonyComponentConsoleInputInputArgument;
use SymfonyComponentConsoleInputInputInterface;
use SymfonyComponentConsoleOutputOutputInterface;
use SymfonyComponentRazvanUtilsCurl;

class ImportCommand extends Command {

 const NEWLINE = true;
 private $connection;

 protected function configure() {
 parent::configure();

 $this
                ->setName('tudorica:razvan')
                ->addArgument('type', InputArgument::REQUIRED, 'Type')
                ->addOption('country', 'c', InputOption::VALUE_OPTIONAL, 'Country', '')

        ;
    }

    /**
     * Executes the current command.
     *
     * @param InputInterface  $input  An InputInterface instance
     * @param OutputInterface $output An OutputInterface instance
     *
     * @return integer 0 if everything went fine, or an error code
     *
     * @throws LogicException When this abstract class is not implemented
     */
    protected function execute(InputInterface $input, OutputInterface $output) {
        // your code here.
        //if you want to access database (must to setup doctrine.dbal)
        $this->connection = $this->container->get('database_connection');

         //to get the user input argument "type" for this command
        $type = $input->getArgument('type');        

        //to get use option "contry" for this command
        $country = $input->getOption('country');

        //to write a message (in symfony1.x was named log).
        $output->write('type: '.$type, true);
    }

}

N

ow, you can open a console and go to app folder. If you write:

./console

you will see something like

router
  :debug                       Displays current routes for an application
  :dump-apache                 Dumps all routes as Apache rewrite rules
tudorica
  :razvan

You can execute this Command with: ./console tudorica:razvan

 

Public, Private, and Protected in PHP

or how to manage access to your classes.

In PHP there are three levels of access for properties and methods from within a class: public, private, and protected.

Public access is the default setting for method and for properties.

  • Public properties and methods can be accessed from any context.
  • Private methods and properties can ONLY be accessed from within the enclosing class. Thesubclasses have no access to them.
  • Protected methods and properties can be accessed from within the enclosing class and fromsubclasses.

According with Zend Coding Standards, variables that are declared with the “private” or “protected” modifier, the first character of the variable name must be a single underscore.

eg: private $_myVar;