array( $this, 'expr' ), ); return $this->getEngine()->registerInterface( __DIR__ . '/mw.ext.ParserFunctions.lua', $lib, array() ); } public function expr( $expression = null ) { $this->checkType( 'mw.ext.ParserFunctions.expr', 1, $expression, 'string' ); try { return array( ExtParserFunctions::getExprParser()->doExpression( $expression ) ); } catch ( ExprError $e ) { throw new Scribunto_LuaError( $e->getMessage() ); } } }