include_path前提のnamespace対応autoload実装(namespaceとpearの併設エラー検証)

autoload.function.php

<?php
return function($className) {
    $className = ltrim($className, '\\');
    if (false !== ($pos = strrpos($className, '\\'))) {
        $namespace = substr($className, 0, $pos);
        $className = substr($className, $pos + 1);
        $fileName = str_replace('\\', DIRECTORY_SEPARATOR, $namespace)
            . DIRECTORY_SEPARATOR
            . str_replace('_', DIRECTORY_SEPARATOR, $className);
    } else {
        $fileName = str_replace('_', DIRECTORY_SEPARATOR, $className);
    }
    if (false !== ($path = stream_resolve_include_path($fileName . '.php'))) {
        return include $path;
    }
    return false;
};

autoload_namespace.php

<?php
namespace Acme;

set_include_path(implode(PATH_SEPARATOR, array(
    '/path/to/vendor',
    get_include_path(),
)));

spl_autoload_register(
    include __DIR__ . DIRECTORY_SEPARATOR . 'autoload.function.php', true, true
);

$ns = new Klass();
var_dump(get_class($ns)); // string(10) "Acme\Klass"

$ns = new \Acme\Klass();
var_dump(get_class($ns)); // string(10) "Acme\Klass"

autoload_namespace_and_pear.php

<?php
namespace Acme;

set_include_path(implode(PATH_SEPARATOR, array(
    '/path/to/pear',
    '/path/to/vendor',
    get_include_path(),
)));

spl_autoload_register(
    include __DIR__ . DIRECTORY_SEPARATOR . 'autoload.function.php', true, true
);

$pear = new \PEAR_Exception('GRRRR');
var_dump(get_class($pear)); // string(14) "PEAR_Exception"

$ns = new Klass();
// include_pathがpear;vendorの順だと、"Class 'Acme\Klass' not found in /path/to/autoload.php" (\Acme\Klassのロードでpearディレクトリから読み込もうとする)
var_dump(get_class($ns)); // string(10) "Acme\Klass"

$ns = new \Acme\Klass();
var_dump(get_class($ns)); // string(10) "Acme\Klass"

$pear = new \Acme_Klass();
// include_pathがvendor;pearの順だと、"Cannot redeclare class Acme\Klass in /path/to/vendor/Acme/Klass.php" (\Acme_Klassのロードでvendorディレクトリから読み込もうとする)
var_dump(get_class($pear)); // string(10) "Acme_Klass"

autoload_pear.php

<?php
set_include_path(implode(PATH_SEPARATOR, array(
    '/path/to/pear',
    get_include_path(),
)));

spl_autoload_register(
    include __DIR__ . DIRECTORY_SEPARATOR . 'autoload.function.php', true, true
);

$pear = new PEAR_Exception('GRRRR');
var_dump(get_class($pear)); // string(14) "PEAR_Exception"

$pear = new Acme_Klass();
var_dump(get_class($pear)); // string(10) "Acme_Klass"

return function(){};されたファイルをinclude、サンプル提示に便利(ﾟ∀ﾟ)