silverstripe-framework/dev/Deprecation.php

<?php

/**
 * Handles raising an notice when accessing a deprecated method
 *
 * A pattern used in SilverStripe when deprecating a method is to add something like
 *   user_error('This method is deprecated', E_USER_NOTICE);
 * to the method
 *
 * However sometimes we want to mark that a method will be deprecated in some future version and shouldn't be used in
 * new code, but not forbid in the current version - for instance when that method is still heavily used in framework
 * or cms.
 *
 * This class abstracts the above pattern and adds a way to do that.
 *
 * Each call to notice passes a version that the notice will be valid from. Additionally this class has a notion of the
 * version it should use when deciding whether to raise the notice. If that version is equal to or greater than the
 * notices version (and SilverStripe is in dev mode) a deprecation message will be raised.
 *
 * Normally the checking version will be the release version of SilverStripe, but a developer can choose to set it to a
 * future version, to see how their code will behave in future versions.
 *
 * Modules can also set the version for calls they make - either setting it to a future version in order to ensure
 * forwards compatibility or setting it backwards if a module has not yet removed references to deprecated methods.
 *
 * When set per-module, only direct calls to deprecated methods from those modules are considered - if the module
 * calls a non-module method which then calls a deprecated method, that call will use the global check version, not
 * the module specific check version.
 *
 * @package framework
 * @subpackage dev
 */
class Deprecation {

	const SCOPE_METHOD = 1;
	const SCOPE_CLASS = 2;
	const SCOPE_GLOBAL = 4;

	/**
	 *
	 * @var string
	 */
	protected static $version;

	/**
	 * Override whether deprecation is enabled. If null, then fallback to
	 * SS_DEPRECATION_ENABLED, and then true if not defined.
	 *
	 * Deprecation is only available on dev.
	 *
	 * Must be configured outside of the config API, as deprecation API
	 * must be available before this to avoid infinite loops.
	 *
	 * @var boolean|null
	 */
	protected static $enabled = null;

	/**
	 *
	 * @var array
	 */
	protected static $module_version_overrides = array();

	/**
	 * @var int - the notice level to raise on a deprecation notice. Defaults to E_USER_DEPRECATED if that exists,
	 * E_USER_NOTICE if not
	 */
	public static $notice_level = null;

	/**
	 * Set the version that is used to check against the version passed to notice. If the ::notice version is
	 * greater than or equal to this version, a message will be raised
	 *
	 * @static
	 * @param $ver string -
	 *     A php standard version string, see http://php.net/manual/en/function.version-compare.php for details.
	 * @param null $forModule string -
	 *    The name of a module. The passed version will be used as the check value for
	 *    calls directly from this module rather than the global value
	 * @return void
	 */
	public static function notification_version($ver, $forModule = null) {
		if ($forModule) {
			self::$module_version_overrides[$forModule] = $ver;
		}
		else {
			self::$version = $ver;
		}
	}

	/**
	 * Given a backtrace, get the module name from the caller two removed (the caller of the method that called
	 * #notice)
	 *
	 * @static
	 * @param $backtrace array - a backtrace as returned from debug_backtrace
	 * @return string - the name of the module the call came from, or null if we can't determine
	 */
	protected static function get_calling_module_from_trace($backtrace) {
		if (!isset($backtrace[1]['file'])) return;

		$callingfile = realpath($backtrace[1]['file']);

		$manifest = SS_ClassLoader::instance()->getManifest();
		foreach ($manifest->getModules() as $name => $path) {
			if (strpos($callingfile, realpath($path)) === 0) {
				return $name;
			}
		}
	}

	/**
	 * Given a backtrace, get the method name from the immediate parent caller (the caller of #notice)
	 *
	 * @static
	 * @param $backtrace array - a backtrace as returned from debug_backtrace
	 * @param $level - 1 (default) will return immediate caller, 2 will return caller's caller, etc.
	 * @return string - the name of the method
	 */
	protected static function get_called_method_from_trace($backtrace, $level = 1) {
		$level = (int)$level;
		if(!$level) $level = 1;
		$called = $backtrace[$level];

		if (isset($called['class'])) {
			return $called['class'] . $called['type'] . $called['function'];
		}
		else {
			return $called['function'];
		}
	}

	/**
	 * Determine if deprecation notices should be displayed
	 *
	 * @return bool
	 */
	public static function get_enabled() {
		// Deprecation is only available on dev
		if(!Director::isDev()) {
			return false;
		}
		if(isset(self::$enabled)) {
			return self::$enabled;
		}
		if(defined('SS_DEPRECATION_ENABLED')) {
			return SS_DEPRECATION_ENABLED;
		}
		return true;
	}

	/**
	 * Toggle on or off deprecation notices. Will be ignored in live.
	 *
	 * @param bool $enabled
	 */
	public static function set_enabled($enabled) {
		self::$enabled = $enabled;
	}

	/**
	 * Raise a notice indicating the method is deprecated if the version passed as the second argument is greater
	 * than or equal to the check version set via ::notification_version
	 *
	 * @param string $atVersion The version at which this notice should start being raised
	 * @param string $string The notice to raise
	 * @param bool $scope Notice relates to the method or class context its called in.
	 */
	public static function notice($atVersion, $string = '', $scope = Deprecation::SCOPE_METHOD) {
		if(!static::get_enabled()) {
			return;
		}

		$checkVersion = self::$version;
		// Getting a backtrace is slow, so we only do it if we need it
		$backtrace = null;

		// If you pass #.#, assume #.#.0
		if(preg_match('/^[0-9]+\.[0-9]+$/', $atVersion)) $atVersion .= '.0';
		if(preg_match('/^[0-9]+\.[0-9]+$/', $checkVersion)) $checkVersion .= '.0';

		if(self::$module_version_overrides) {
			$module = self::get_calling_module_from_trace($backtrace = debug_backtrace(0));
			if(isset(self::$module_version_overrides[$module])) {
				$checkVersion = self::$module_version_overrides[$module];
			}
		}

		// Check the version against the notice version
		if ($checkVersion && version_compare($checkVersion, $atVersion, '>=')) {
			// Get the calling scope
			if($scope == Deprecation::SCOPE_METHOD) {
				if (!$backtrace) $backtrace = debug_backtrace(0);
				$caller = self::get_called_method_from_trace($backtrace);
			} elseif($scope == Deprecation::SCOPE_CLASS) {
				if (!$backtrace) $backtrace = debug_backtrace(0);
				$caller = isset($backtrace[1]['class']) ? $backtrace[1]['class'] : '(unknown)';
			} else {
				$caller = false;
			}

			// Get the level to raise the notice as
			$level = self::$notice_level;
			if (!$level) $level = E_USER_DEPRECATED;

			// Then raise the notice
			if(substr($string,-1) != '.') $string .= ".";

			$string .= " Called from " . self::get_called_method_from_trace($backtrace, 2) . '.';

			if($caller) {
				user_error($caller.' is deprecated.'.($string ? ' '.$string : ''), $level);
			} else {
				user_error($string, $level);
			}

		}
	}

	/**
	 * Method for when testing. Dump all the current version settings to a variable for later passing to restore
	 *
	 * @return array Opaque array that should only be used to pass to {@see Deprecation::restore_settings()}
	 */
	public static function dump_settings() {
		return array(
			'level' => self::$notice_level,
			'version' => self::$version,
			'moduleVersions' => self::$module_version_overrides,
			'enabled' => self::$enabled,
		);
	}

	/**
	 * Method for when testing. Restore all the current version settings from a variable
	 *
	 * @param $settings array An array as returned by {@see Deprecation::dump_settings()}
	 */
	public static function restore_settings($settings) {
		self::$notice_level = $settings['level'];
		self::$version = $settings['version'];
		self::$module_version_overrides = $settings['moduleVersions'];
		self::$enabled = $settings['enabled'];
	}
}