Class Autoloading

Class Autoloading

“Class Autoloading” means: “when I want to use a class, I simply attempt to instantiate it (ie: new Foo()) and PHP will automatically find the right file, load it (so I don’t have to include() or require() it manually), and then do the requested creation of an instance of it”. In most cases this is the best way.

Encapsulated plugins allow you to Autoload classes based on 2 scenarios.

• Where the class follows PSR4 and the filename is the same as the class name (This is the best way). Naming should be CamelCased.
• Where the filename is different to the class name (This should be rare).

PSR4 based classes

Formula for catalog:

• place your class in the plugin’s [version]/catalog/includes/classes/ directory
• name the class and its filename the same (ie: catalog/includes/classes/DrawPrettyGraph.php should contain a class named DrawPrettyGraph)
• set the namespace: namespace Zencart\Plugins\Catalog\SalesGraphs; if the plugin’s name is Sales Graphs

Formula for admin: (basically, change “catalog” to “admin” for directory name and namespace)

• place your class in the plugin’s [version]/admin/includes/classes/ directory
• name the class and its filename the same (ie: admin/includes/classes/DrawPrettyGraph.php should contain a class named DrawPrettyGraph)
• set the namespace: namespace Zencart\Plugins\Admin\SalesGraphs; if the plugin’s name is Sales Graphs

Example, for a plugin named Sales Graphs:

Filename

zc_plugins/SalesGraphs/vX.Y/admin/includes/classes/DrawPrettyGraph.php

Contents

<?php
namespace Zencart\Plugins\Admin\DisplayLogs;

class DrawPrettyGraph
{
    public function output()
    {
        echo 'Look at my pretty graph!';
    }
}

Invoking

now in any file you can invoke it directly: $myGraph = (new ZenCart\Plugins\Admin\SalesGraphs\DrawPrettyGraph)->output();

Or if you’d like to split the namespace out separately to make lines shorter, use 2 steps:

• At the top of whatever file you wish to use it, add a line: use Zencart\Plugins\Admin\SalesGraphs\DrawPrettyGraph;
• Then call it: $myGraph = (new DrawPrettyGraph)->output();

Custom class filenames

When the filename of a class does not match the class name, we need to do a bit more work.

From the example above, if we had a class filename of class.some_weird_class_filename.php and the class name was myClass, then we would have to set up autoloading manually at tthe top of whatever file needs it. The following would need to be called after the line require 'includes/application_top.php';:

$psr4Autoloader->setClassFile('Zencart\Plugins\Admin\SalesGraphs\myClass', $filePathPluginAdmin['SalesGraphs'] . 'class.some_weird_class_filename.php');
$myClass = new Zencart\Plugins\Admin\SalesGraphs\myClass();
$myClass->output();

This would output 'Look at my pretty graph!'