I do not understand calling sale function of new product

Posted on 2014-03-25
Medium Priority
Last Modified: 2014-03-30
require_once( "closures.php" );

$logger = create_function( '$product', 
                           'print "    logging ({$product->name})\n";' );

$processor = new ProcessSale();
$processor->registerCallback( $logger );

$processor->sale( new Product( "shoes", 6 ) );
print "\n";
$processor->sale( new Product( "coffee", 6 ) );

Open in new window


class Product {
    public $name;
    public $price;
    function __construct( $name, $price ) {
        $this->name = $name;
        $this->price = $price;

class ProcessSale {
    private $callbacks;

    function registerCallback( $callback ) {
        if ( ! is_callable( $callback ) ) {
            throw new Exception( "callback not callable" );
        $this->callbacks[] = $callback;

    function sale( $product ) {
        print "{$product->name}: processing \n";
        foreach ( $this->callbacks as $callback ) {
            call_user_func( $callback, $product );

Open in new window

I do not understand calling sale function of new product

$processor->sale( new Product( "shoes", 6 ) );
Question by:rgb192
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 2
LVL 35

Expert Comment

ID: 39955054
What specifically do you not understand about it?

To be clear, the sale function does not belong to the new product. The sale function belongs to the $processor object, and the code is creating a new product object and passing that new product as a parameter to the $processor's sale function.

Author Comment

ID: 39956570
Calling 2 methods at the same time

Author Comment

ID: 39962398
I do not understand calling two classes at the same time.

Sale method of new product
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

LVL 35

Accepted Solution

gr8gonzo earned 2000 total points
ID: 39963127
This code:
$processor->sale( new Product( "shoes", 6 ) );

...could be rewritten as two lines:

$temporary_variable = new Product( "shoes", 6 );
$processor->sale( $temporary_variable );

The only difference is that the "new Product" part is created in memory and is passed immediately to the sale function and there is no $temporary_variable or other variable to reference it outside of the function.

Author Comment

ID: 39964987
okay same output but easier to understand

//$processor->sale( new Product( "shoes", 6 ) );
$temporary_variable=new Product("shoes", 6);

Next part of sale function I do not understand is the foreach
this run was value lambda_8, last run was lambda_8
Only one run in the foreach

what is lambda and why always run once

Author Closing Comment

ID: 39965428
Yes you answered the question about calling the method.
Thank you.

Second question about this method is:

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Password hashing is better than message digests or encryption, and you should be using it instead of message digests or encryption.  Find out why and how in this article, which supplements the original article on PHP Client Registration, Login, Logo…
This article discusses four methods for overlaying images in a container on a web page
The viewer will learn how to dynamically set the form action using jQuery.
The viewer will learn how to look for a specific file type in a local or remote server directory using PHP.
Suggested Courses

777 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question