关于c：使抽象的方法具有用于重写的主体


make abstract a method with body for overriding

我有我的饮料课，它有一些与饮料大小相关的getter/setter。这个程序与decorator模式有关，所以我想结合一些同样命名的方法的行为。

我的目的是要有一个身体的方法，允许我获得饮料的大小，但然后，我想能够覆盖儿童班的行为。

总之，我想要一种方法：

  • 如果不重写，则只表现为父类中的方法
  • 如果重写，则行为类似于对其进行编码

我所做的是创建一个名为getsizeofbeverage的方法，该方法的行为与我的"旧"getsize类似，并将getsizeofbeverage抽象为"新"方法，以便我可以重写它，但我需要一个不暗示新方法名的解决方案。

这是我的代码：

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using System;

namespace Decorator
{
    class Program
    {
        static void Main(string[] args)
        {
            Beverage beverage = new Espresso("small");
            beverage = new Whip(beverage);
            Console.WriteLine(beverage.getDescription() +" $" + beverage.cost());
        }
    }

    abstract class Beverage
    {
      private string description;
      private string size;

      public Beverage()
      {
        setDescription("Unknown beverage");
      }

      public double getCost()
      {
        return cost();
      }

      public abstract double cost();

      public abstract string getDescription();

      public void setDescription(string desc)
      {
        description = desc;
      }

      public string getSizeOfBeverage()
      {
        return size;
      }

      public abstract string getSize();

      public void setSize(string sz)
      {
        size = sz;
      }
    }

    class Espresso : Beverage
    {
      public Espresso(string sz)
      {
        setSize(sz);
        setDescription("Espresso");
      }

      public override double cost()
      {
        return 1.9;
      }

      public override string getDescription()
      {
        return getDescription();
      }

      public override string getSize()
      {
        return getSizeOfBeverage();
      }
    }

    abstract class CondimentDecorator : Beverage
    {
      public abstract override string getSize();
    }

    class Whip : CondimentDecorator
    {
      private Beverage beverage;

      public Whip(Beverage bv)
      {
        beverage = bv;
      }

      public override double cost()
      {
        if (getSize() =="small")
        {
          return 0.1 + beverage.cost();
        }
        else if (getSize() =="medium")
        {
          return 0.15 + beverage.cost();
        }
        else
        {
          return 0.2 + beverage.cost();
        }
      }

      public override string getDescription()
      {
        return beverage.getDescription() +", whip";
      }

      public override string getSize()
      {
        return beverage.getSizeOfBeverage();
      }
    }
}

if not overriden, just behaves as the method in the parent class if

overriden, behaves like it is coded

每个virtual方法的工作原理如下：

如果它被重写，它的行为将与被编码的行为类似，如果它不只是作为父类中的方法进行操作

从文档中获取虚拟

The virtual keyword is used to modify a method, property, indexer, or
event declaration and allow for it to be overridden in a derived
class. For example, this method can be overridden by any class that
inherits it:

抽象

When an instance method declaration includes an abstract modifier,
that method is said to be an abstract method. Although an abstract
method is implicitly also a virtual method, it cannot have the
modifier virtual. An abstract method declaration introduces a new
virtual method but does not provide an implementation of that method.
Instead, non-abstract derived classes are required to provide their
own implementation by overriding that method. Because an abstract
method provides no actual implementation, the method-body of an
abstract method simply consists of a semicolon.

在C中查看虚方法和抽象方法的区别#