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authorDries Buytaert2008-12-02 19:33:33 (GMT)
committerDries Buytaert2008-12-02 19:33:33 (GMT)
commit8900c6156d3ab1e48c8e8ff697305ce6530fbe5a (patch)
tree456585ba2fdbc0bfc72222ee65db26990c86215a
parentf3ad4d956825958798de4cd7b5cbcc7dd3f1ab1b (diff)
- Patch #336115 by nedjo: additional documentation for t().
-rw-r--r--includes/common.inc99
1 files changed, 97 insertions, 2 deletions
diff --git a/includes/common.inc b/includes/common.inc
index b6a55bc..6301b64 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -847,7 +847,7 @@ function fix_gpc_magic() {
/**
* Translate strings to the page language or a given language.
*
- * All human-readable text that will be displayed somewhere within a page should
+ * Human-readable text that will be displayed somewhere within a page should
* be run through the t() function.
*
* Examples:
@@ -914,7 +914,7 @@ function fix_gpc_magic() {
* $output .= '<p>' . t('Go to the <a href="@contact-page">contact page</a>.', array('@contact-page' => url('contact'))) . '</p>';
* @endcode
*
- * Also avoid escaping quotation marks wherever possible.
+ * Avoid escaping quotation marks wherever possible.
*
* Incorrect:
* @code
@@ -926,6 +926,101 @@ function fix_gpc_magic() {
* $output .= t("Don't click me.");
* @endcode
*
+ * Because t() is designed for handling code-based strings, in almost all
+ * cases, the actual string and not a variable must be passed through t().
+ *
+ * Extraction of translations is done based on the strings contained in t()
+ * calls. If a variable is passed through t(), the content of the variable
+ * cannot be extracted from the file for translation.
+ *
+ * Incorrect:
+ * @code
+ * $message = 'An error occurred.';
+ * drupal_set_message(t($message), 'error');
+ * $output .= t($message);
+ * @endcode
+ *
+ * Correct:
+ * @code
+ * $message = t('An error occurred.');
+ * drupal_set_message($message, 'error');
+ * $output .= $message;
+ * @endcode
+ *
+ * The only case in which variables can be passed safely through t() is when
+ * code-based versions of the same strings will be passed through t() (or
+ * otherwise extracted) elsewhere.
+ *
+ * In some cases, modules may include strings in code that can't use t()
+ * calls. For example, a module may use an external PHP application that
+ * produces strings that are loaded into variables in Drupal for output.
+ * In these cases, module authors may include a dummy file that passes the
+ * relevant strings through t(). This approach will allow the strings to be
+ * extracted.
+ *
+ * Sample external (non-Drupal) code:
+ * @code
+ * class Time {
+ * public $yesterday = 'Yesterday';
+ * public $today = 'Today';
+ * public $tomorrow = 'Tomorrow';
+ * }
+ * @endcode
+ *
+ * Sample dummy file.
+ * @code
+ * // Dummy function included in example.potx.inc.
+ * function example_potx() {
+ * $strings = array(
+ * t('Yesterday'),
+ * t('Today'),
+ * t('Tomorrow'),
+ * );
+ * // No return value needed, since this is a dummy function.
+ * }
+ * @endcode
+ *
+ * Having passed strings through t() in a dummy function, it is then
+ * okay to pass variables through t().
+ *
+ * Correct (if a dummy file was used):
+ * @code
+ * $time = new Time();
+ * $output .= t($time->today);
+ * @endcode
+ *
+ * However tempting it is, custom data from user input or other non-code sources
+ * should not be passed through t(). Doing so leads to the following
+ * problems and errors:
+ * - The t() system doesn't support updates to existing strings. When user data
+ * is updated, the next time it's passed through t() a new record is created
+ * instead of an update. The database bloats over time and any existing
+ * translations are orphaned with each update.
+ * - The t() system assumes any data it receives is in English. User data may
+ * be in another language, producing translation errors.
+ * - The "Built-in interface" text group in the locale system is used to produce
+ * translations for storage in .po files. When non-code strings are passed
+ * through t(), they are added to this text group, which is rendered inaccurate
+ * since it is a mix of actual interface strings and various user input strings of
+ * uncertain origin.
+ *
+ * Incorrect:
+ * @code
+ * $item = item_load();
+ * $output .= check_plain(t($item['title']));
+ * @endcode
+ *
+ * Instead, translation of these data can be done through the locale system,
+ * either directly or through helper functions provided by contributed
+ * modules.
+ * @see hook_locale()
+ *
+ * During installation, st() is used in place of t(). Code that may be called
+ * during installation or during normal operation should use the get_t()
+ * helper function.
+ * @see st()
+ * @see get_t()
+ *
* @param $string
* A string containing the English string to translate.
* @param $args