Generating other classes beside the core ones

There is a complete lack of documentation on creating custom generators, but its a slight abstract of the Zend code generator. Which you will probs have a better time find documentation for. But in terms of registering a new generator in Magento it's basically 2 steps to do so.

https://framework.zend.com/manual/2.4/en/modules/zend.code.generator.examples.html

Create the generator

Generators are extended from the Magento\Framework\Code\Generator\EntityAbstract class and require the following methods are defined _getDefaultConstructorDefinition _getClassMethods.

Good examples imo to work from are either the factory or proxy generators. \Magento\Framework\ObjectManager\Code\Generator\Factory \Magento\Framework\ObjectManager\Code\Generator\Proxy

But a basic generator would look something along the lines of

app/code/Bigeyedeers/Generator/Code/Generator/Example.php 

<?php namespace Bigeyedeers\Generated\Code\Generator; class Example extends \Magento\Framework\Code\Generator\EntityAbstract { const ENTITY_TYPE = 'example'; protected function _getDefaultConstructorDefinition() { return [ 'name' => '__construct', 'parameters' => [ ['name' => 'objectManager', 'type' => '\\' . \Magento\Framework\ObjectManagerInterface::class], ['name' => 'instanceName', 'defaultValue' => $this->getSourceClassName()], ], 'body' => "\$this->_objectManager = \$objectManager;\n\$this->_instanceName = \$instanceName;", 'docblock' => [ 'shortDescription' => ucfirst(static::ENTITY_TYPE) . ' constructor', 'tags' => [ [ 'name' => 'param', 'description' => '\Magento\Framework\ObjectManagerInterface $objectManager', ], ['name' => 'param', 'description' => 'string $instanceName'], ], ] ]; } protected function _getClassMethods() { $construct = $this->_getDefaultConstructorDefinition(); // public function create(array $data = array()) $create = [ 'name' => 'create', 'parameters' => [['name' => 'data', 'type' => 'array', 'defaultValue' => []]], 'body' => 'return $this->_objectManager->create($this->_instanceName, $data);', 'docblock' => [ 'shortDescription' => 'Create class instance with specified parameters', 'tags' => [ ['name' => 'param', 'description' => 'array $data'], [ 'name' => 'return', 'description' => $this->getSourceClassName() ], ], ], ]; return [$construct, $create]; } } 

Update the generated entities array

I was having trouble adding a new item node into the type declaration from a module. Im sure with more time you'd be able to work it out.

But within app/etc/di.xml add a new item node to the generatedEntities argument of the Magento\Framework\Code\Generator type declartion that points to your new generator class.

app/etc/di.xml 

... <type name="Magento\Framework\Code\Generator"> <arguments> <argument name="generatedEntities" xsi:type="array"> <item name="example" xsi:type="string">\Bigeyedeers\Generated\Code\Generator\Example</item> ... 

Usage

Now you can inject your generated class just like proxies/factories etc. When you compile then it should pull your new generated class

public function __construct(\Magento\Catalog\Model\CategoryExample $categoryExample) { $this->_categoryExample = $categoryExample; } 

Edit by OP
In order not to change the core file app/etc/di.xml, the configuration can be added in app/etc/additional/di.xml (or any other subfolder of app/etc/) and it will be picked up by the config loader automatically.

<?xml version="1.0"?> <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd"> <type name="Magento\Framework\Code\Generator"> <arguments> <argument name="generatedEntities" xsi:type="array"> <item name="example" xsi:type="string">\Bigeyedeers\Generated\Code\Generator</item> </argument> </arguments> </type> </config>