装饰器模式浪费内存 [英] Decorator pattern wasting memory

问题描述

我有一个具有以下接口的基类:

I have this base class having the following interface:

abstract class Base
{
  abstract public object Val
  {
    get;
  }
}

对于任何派生类，必须在对象创建时指定Val的值 .
问题是:我如何使成为派生类(希望在编译时)做到这一点?
我尝试添加一个构造函数:

For any derived classes, Val's value must be specified at object creation time.
The question is: How can I make a derived class do this (hopefully at compile time)?
I tried adding a constructor:

abstract class Base
{
  public Base(object value)
  {
    val = value;
  }

  private object val;

  ...
}

但是正如您所看到的，我不得不声明一个私有字段来在其中存储值(因为Value是只读的).
出现问题是因为我想使用GoF设计模式中引入的Decorator/Wrapper模式向派生类添加某种效果.但是因为我已经在Base类中声明了该字段，所以装饰器不断保存相同数据的副本，最终浪费了内存.

But as you can see then I had to declare a private field to store value in it (because Value is read-only).
The problem arises because I want to add some kind of effect to derived classes using the Decorator/Wrapper pattern introduced in GoF Design Patterns. But because I have declared the field inside Base class, the decorators keep saving a copy of the same data and I end up wasting memory.

推荐答案

尝试以下方法:

abstract class Base 
{
    public Base(object val)
    {
        this.Val = val;
    }

    public object Val { get; private set; }
}

这样，您的派生类就不需要自己的字段:

That way, your derived class doesn't need its own field:

public class Derived : Base
{
    public Derived(object val) : base(val) { }
}

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