屬性的出現有對類型系統的一些影響。最重要的是，有必要理解屬性是一個編譯時功能，因此需要類型是已知的。如果我們要分配一個類的屬性為Dynamic，字段訪問不會遵守存取器方法。同樣，訪問限制不再應用，所有的訪問是幾乎公開的。 > The presence of properties has several consequences on the type system. Most importantly, it is necessary to understand that properties are a compile-time feature and thus require the types to be known. If we were to assign a class with properties to Dynamic, ?eld access would not respect accessor methods. Likewise,access restrictions no longer apply and all access is virtually public. 當使用get 或者set 訪問標識符，編譯器確保getter 和setter實際上存在。下面的問題不會編譯： > Whenusing get or set accessidenti?er,the compiler ensures that the getter and setter actually exists. The following problem does not compile: ~~~ class Main { // Method get_x required by property x is missing public var x(get, null):Int; static public function main() {} } ~~~ 方法 get_x 丟失了，但是它不必被定義到屬性自己的類定義中，只要一個父類中定義了它： > The method get_x is missing, but it need not be declared on the class de?ning the property itself as long as a parent class de?nes it: ~~~ class Base { public function get_x() return 1; } class Main extends Base { // ok, get_x is declared by parent class public var x(get, null):Int; static public function main() {} } ~~~ dynamic 訪問修飾符正常的工作就像get 或者 set，但是不會檢查存在與否。 > The dynamic access modi?er works exactly like get or set, but does not check for the existence