在扩展类中覆盖构造函数（Decorator模式）

Question

Suppose I have a base abstract class Base that is extended by the classes Base1 , Base2 , and Base 3 . It takes into its constructor an object containing information that I want to access in my decorator classes, Decorator1 and Decorator2 . The decorator classes extend Decorator which, in turn, extends Base .

InfoNeeded i = new InfoNeeded(user_input);
Base a = new Base1(i);
a = new Decorator1(a);
a = new Decorator2(a);
// etc...

My issue is that I need to access i.getSomeValue1() , i.getSomeValue2() , etc... within Decorator1 and Decorator2 . At first I tried putting a constructor to grab i in my abstract class Base . Then I implemented all of my getSomeValue() functions in there so I could just call a.getSomeValue() to pull the info I need. However, this caused issues because Decorator extends Base , forcing its constructor to take in i rather than a .

Is there a way to override the constructor in an extended class so that it's not forced to take in something I don't want?

Right now, I have my getSomeValue() functions copied and pasted among all of my base classes and decorator classes which works, but feels gross. I'd love to figure out a way to avoid this repetition. Thanks!

Answer 1

The answer is no, you cannot override a constructor. If the parent class needs something, you must make it available.

But, you can have more than one constructor, maybe this helps?

On the repetition of the getSomeValue() method, could you put it in the Base class so that all the others have it?