Delphi中的抽象类 [英] Abstract Class in Delphi

问题描述

我正在使用具有许多抽象类的组件套件。现在，我想应用多态性，但是在创建对象时遇到了错误抽象类。

I am using a component suite which has many abstract classes. Now I want to apply polymorphism but I am getting Error Abstract Class when I create my object.

即使我不需要虚拟方法，我也应该重写它吗？有任何解决方法或解决方案吗？

Should I override all methods which are virtual even if I don't need it? Are there any workaround or solution?

推荐答案

为了创建类的实例，您需要覆盖所有声明为虚拟摘要。即使您不使用它们。

In order to make an instance of a class, you need to override all methods that are declared as virtual abstract. Even if you don't use them.

如果您确实想要解决问题，则可以使用空方法。但我不建议这样做。

If you really want a work around, you can use empty methods. But I won't recommend that.

并添加有关该主题的更多信息：

And to add some more information on the subject:

一种方法如果用虚拟抽象声明，则为抽象：

A method is abstract if it is declared with virtual abstract:

procedure MyMethod(const AMyParameter: Integer); virtual; abstract;

琐事：您甚至可以覆盖抽象方法：

Trivia: You can even override a method as abstract:

procedure MyMethod(const AMyParameter: Integer); override; abstract;

您需要重写这些方法才能从该类实例化。

You need to override these methods in order to instantiate from that class.

您可以将整个类声明为抽象类：

And you can declare an entire class as abstract:

type
  TMyClass = class abstract (TMyAncestor)
  end;

如果尝试实例化该类，则会收到警告。

You get a warning if you try to instantiate that class.

对方是密封类：

type
  TMyClass = class sealed (TMyAncestor)
  end;

如果尝试从该类继承，则会收到警告。

You get a warning if you try to inherit from that class.

您也可以密封方法，但是您需要使用关键字final。

You can also seal methods, but you need the keyword final for that.

procedure MyMethod(const AMyParameter: Integer); override; final;

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