调用 this() 构造函数和不同的 base() 构造函数

Question

我有一些 class 都扩展了父 class。像这样：

public abstract class EasyUIELementFoundation
{
    protected GameObject UIElement;
    private RectTransform RectOptions;
    private Vector2 _position;
    private Vector2 _dimensions;

    protected Vector2 Position
    {
        get
        {
            return _position;
        }
        set
        {
            RectOptions.pivot = value;
            _position = value;
        }
    }

    protected Vector2 Dimensions
    {
        get
        {
            return _dimensions;
        }
        set
        {
            RectOptions.sizeDelta = value;
            _dimensions = value;
        }
    }

    protected EasyUIELementFoundation()
    {
        UIElement = new GameObject();
        RectOptions = UIElement.AddComponent(typeof(RectTransform)) as RectTransform;
    }

    protected EasyUIELementFoundation(Vector2 position) : this()
    {
        _position = position;
    }

    protected EasyUIELementFoundation(Vector2 position, Vector2 dimensions) : this()
    {
        _dimensions = dimensions;
        _position = position;
    }
}

public class EasyRawImage : EasyUIELementFoundation
{
    private RawImage UIImageComponent;
    private Texture2D _image;

    public Texture2D Image
    {
        get
        {
            return _image;
        }
        set
        {
            UIImageComponent.texture = value;
            _image = value;
        }
    }

    public EasyRawImage() : base()
    {
        UIImageComponent = UIElement.AddComponent(typeof(RawImage)) as RawImage;
    }

    public EasyRawImage(UnityEngine.Object image, Vector2 position) : this() : base(position)  
    // here is the error it is not possible to call the base.
    {
         //some code...
    }
}

所以我的问题是我有 3 个不同的基础 class 构造函数，我想从派生的 class 调用不同的基础构造函数，但我不能 atm。这甚至可能吗？如果不能，我将如何做这样的事情？

如果有任何不清楚的地方，请告诉我，以便我澄清。
我是 OOP 的新手，如果这是一个奇怪的问题，我很抱歉。

Answer 1

调用 this() 将隐式或显式调用基构造函数。因此，base 的另一次调用将是您第二次构造同一个对象，这是不允许的。

您可以通过创建私有辅助方法来共享构造函数的代码，如下所示：

public class EasyRawImage : EasyUIELementFoundation
{
    private RawImage UIImageComponent;
    private Texture2D _image;

    public Texture2D Image
    {
        get
        {
            return _image;
        }
        set
        {
            UIImageComponent.texture = value;
            _image = value;
        }
    }

    public EasyRawImage() : base()
    {
        InitUiImageComponent();
    }

    public EasyRawImage(UnityEngine.Object image, Vector2 position) : base(position)  
    {
        InitUiImageComponent();
         //some code...
    }
    private void InitUiImageComponent() {
        UIImageComponent = UIElement.AddComponent(typeof(RawImage)) as RawImage;
    }

}

在您的特定情况下，可以将初始化代码直接放入初始化程序中，因此不需要辅助方法：

public class EasyRawImage : EasyUIELementFoundation
{
    private RawImage UIImageComponent = UIElement.AddComponent(typeof(RawImage));
    private Texture2D _image;

    public Texture2D Image
    {
        get
        {
            return _image;
        }
        set
        {
            UIImageComponent.texture = value;
            _image = value;
        }
    }

    public EasyRawImage() : base()
    {
    }

    public EasyRawImage(UnityEngine.Object image, Vector2 position) : base(position)  
    {
         //some code...
    }

}

Answer 2

您不能同时调用 this 和基础构造函数。通常最好的方法是如评论中已经提到的那样，首先实现最复杂（具有最多参数）的构造函数并调用基础 class。然后让更简单的构造函数使用默认值调用复杂的构造函数。使用这种方法，您的 class 将最终看起来像这样：

public class EasyRawImage : EasyUIELementFoundation
{
    private RawImage UIImageComponent;
    private Texture2D _image;

    public Texture2D Image
    {
        get
        {
            return _image;
        }
        set
        {
            UIImageComponent.texture = value;
            _image = value;
        }
    }

    public EasyRawImage() : this(default(UnityEngine.Object), default(Vector2))
    {
    }

    public EasyRawImage(UnityEngine.Object image, Vector2 position) : base(position)
    {
         UIImageComponent = UIElement.AddComponent(typeof(RawImage)) as RawImage;
         //some code...
    }
}

调用 this() 构造函数和不同的 base() 构造函数

call this() constructor and different base() constructor

c#

class

oop

constructor

base-class