Generic override XLIFF in TYPO3 CMS

ext_tables.php

<?php

/**
 * Following snippet lets you easily override XLIFF-based localization files for any extension.
 * 
 * Create localization files within your extension in:
 * 
 *     Resources/Private/Language/Overrides/<extension-key>.<original-name>.xlf
 *     Resources/Private/Language/Overrides/<locale>.<extension-key>.<original-name>.xlf
 * 
 * E.g., you want to override EXT:news/Resources/Private/Language/locallang_db.xlf, then create
 * 
 *     Resources/Private/Language/Overrides/news.locallang_db.xlf
 * 
 * and, to override the French localization:
 * 
 *     Resources/Private/Language/Overrides/fr.news.locallang_db.xlf
 * 
 * BEWARE: In order for French (or any other language) override to work, you MUST have the original
 *         French localization for the corresponding extension.
 */
$languageOverridePath = \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::extPath($_EXTKEY) . 'Resources/Private/Language/Overrides/';
$extensionRelativePath = substr($languageOverridePath, strlen(PATH_site));

$languageFiles = \TYPO3\CMS\Core\Utility\GeneralUtility::getFilesInDir($languageOverridePath, 'xlf');
foreach ($languageFiles as $file) {
	$parts = explode('.', $file);

	if (count($parts) === 3) {
		$locale = 'default';
		$extensionKey = $parts[0];
		$languageFile = $parts[1] . '.' . $parts[2];
	} elseif (count($parts) === 4) {
		$locale = $parts[0];
		$extensionKey = $parts[1];
		$languageFile = $parts[2] . '.' . $parts[3];
	} else {
		// Unsupported localization file
		continue;
	}

	$originalLanguageFileName = 'EXT:' . $extensionKey . '/Resources/Private/Language/' . $languageFile;

	if ($locale === 'default') {
		// Register overlay for English localization file
		$GLOBALS['TYPO3_CONF_VARS']['SYS']['locallangXMLOverride'][$originalLanguageFileName][] = $extensionRelativePath . $file;
	} else {
		// Register overlay for a given locale localization file
		$GLOBALS['TYPO3_CONF_VARS']['SYS']['locallangXMLOverride'][$locale][$originalLanguageFileName][] = $extensionRelativePath . $file;
	}
}

Hi Xavier,

I have one additional remark: I realized that you named the Gist file ext_tables.php but the comment in the code says ext_localconf.php.

Useing ext_localconf.php is problematic because then you might run into trouble when you want to override translations of the context_help extension. It makes use of the override mechanism (for including the files from the 4.5 folder). But there the ext_tables.php file is used (which seems to be loaded after ext_tables.php) and therefore your overrides will be ignored.

Cheers,
Alex