Code Generation

Introduction

Zend\Code\Generator provides facilities to generate arbitrary code using an object-oriented interface, both to create new code as well as to update existing code. While the current implementation is limited to generating PHP code, you can easily extend the base class in order to provide code generation for other tasks: JavaScript, configuration files, apache vhosts, etc.

Theory of Operation

In the most typical use case, you will simply instantiate a code generator class and either pass it the appropriate configuration or configure it after instantiation. To generate the code, you will simply echo the object or call its generate() method.

// Passing configuration to the constructor:
$file = new Zend\Code\Generator\FileGenerator(array(
    'classes' => array(
        new Zend\Code\Generator\ClassGenerator(
            'World',  // name
            null,     // namespace
            null,     // flags
            null,     // extends
            array(),  // interfaces
            array(),  // properties
            array(
                new Zend\Code\Generator\MethodGenerator(
                    'hello',                  // name
                    array(),                  // parameters
                    'public',                 // visibility
                    'echo \'Hello world!\';'  // body
                ),
            )
        ),
    ),
));

// Render the generated file
echo $file->generate();

// or write it to a file:
file_put_contents('World.php', $file->generate());

// OR

// Configuring after instantiation
$method = new Zend\Code\Generator\MethodGenerator();
$method->setName('hello')
       ->setBody('echo \'Hello world!\';');

$class = new Zend\Code\Generator\ClassGenerator();
$class->setName('World')
      ->addMethodFromGenerator($method);

$file = new Zend\Code\Generator\FileGenerator();
$file->setClass($class);

// Render the generated file
echo $file->generate();

// or write it to a file:
file_put_contents('World.php', $file->generate());

Both of the above samples will render the same result:

<?php

class World
{

    public function hello()
    {
        echo 'Hello world!';
    }

}

Another common use case is to update existing code -- for instance, to add a method to a class. In such a case, you must first inspect the existing code using reflection, and then add your new method. Zend\Code\Generator makes this trivially simple, by leveraging Zend\Code\Reflection.

As an example, let's say we've saved the above to the file World.php, and have already included it. We could then do the following:

$class = Zend\Code\Generator\ClassGenerator::fromReflection(
    new Zend\Code\Reflection\ClassReflection('World')
);

$method = new Zend\Code\Generator\MethodGenerator();
$method->setName('mrMcFeeley')
       ->setBody('echo \'Hello, Mr. McFeeley!\';');
$class->addMethodFromGenerator($method);

$file = new Zend\Code\Generator\FileGenerator();
$file->setClass($class);

// Render the generated file
echo $file->generate();

// Or, better yet, write it back to the original file:
file_put_contents('World.php', $file->generate());

The resulting class file will now look like this:

<?php

class World
{

    public function hello()
    {
        echo 'Hello world!';
    }

    public function mrMcFeeley()
    {
        echo 'Hellow Mr. McFeeley!';
    }

}