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The Class Map Generator
The Class Map Generator¶
Loading a class usually is an easy task given the PSR-0 and PSR-4 standards. Thanks to the Symfony ClassLoader component or the autoloading mechanism provided by Composer, you don’t have to map your class names to actual PHP files manually. Nowadays, PHP libraries usually come with autoloading support through Composer.
But from time to time you may have to use a third-party library that comes without any autoloading support and therefore forces you to load each class manually. For example, imagine a library with the following directory structure:
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library/ ├── bar/ │ ├── baz/ │ │ └── Boo.php │ └── Foo.php └── foo/ ├── bar/ │ └── Foo.php └── Bar.php
These files contain the following classes:
To make your life easier, the ClassLoader component comes with a
Symfony\Component\ClassLoader\ClassMapGenerator class that makes
it possible to create a map of class names to files.
Generating a Class Map¶
To generate the class map, simply pass the root directory of your class files
use Symfony\Component\ClassLoader\ClassMapGenerator; print_r(ClassMapGenerator::createMap(__DIR__.'/library'));
Given the files and class from the table above, you should see an output like this:
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Array ( [Acme\Foo] => /var/www/library/foo/Bar.php [Acme\Foo\Bar] => /var/www/library/foo/bar/Foo.php [Acme\Bar\Baz] => /var/www/library/bar/baz/Boo.php [Acme\Bar] => /var/www/library/bar/Foo.php )
Dumping the Class Map¶
Writing the class map to the console output is not really sufficient when
it comes to autoloading. Luckily, the
ClassMapGenerator provides the
to save the generated class map to the filesystem:
use Symfony\Component\ClassLoader\ClassMapGenerator; ClassMapGenerator::dump(__DIR__.'/library', __DIR__.'/class_map.php');
This call to
dump() generates the class map and writes it to the
file in the same directory with the following contents:
<?php return array ( 'Acme\\Foo' => '/var/www/library/foo/Bar.php', 'Acme\\Foo\\Bar' => '/var/www/library/foo/bar/Foo.php', 'Acme\\Bar\\Baz' => '/var/www/library/bar/baz/Boo.php', 'Acme\\Bar' => '/var/www/library/bar/Foo.php', );
Instead of loading each file manually, you’ll only have to register the generated
class map with, for example, the
use Symfony\Component\ClassLoader\MapClassLoader; $mapping = include __DIR__.'/class_map.php'; $loader = new MapClassLoader($mapping); $loader->register(); // you can now use the classes: use Acme\Foo; $foo = new Foo(); // ...
The example assumes that you already have autoloading working (e.g. through Composer or one of the other class loaders from the ClassLoader component.
Besides dumping the class map for one directory, you can also pass an array of directories for which to generate the class map (the result actually is the same as in the example above):
use Symfony\Component\ClassLoader\ClassMapGenerator; ClassMapGenerator::dump( array(__DIR__.'/library/bar', __DIR__.'/library/foo'), __DIR__.'/class_map.php' );
This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.