C#中的模拟方法级联

Question

Dart编程语言支持方法级联.方法级联将允许以下Silverlight/WPF C#代码:

var listBox = new ListBox();

listBox.Width = 200;
listBox.MouseEnter += (s, e) => Console.WriteLine("MouseEnter");

var button1 = new Button() { Content = "abc" };
button1.Click += (s, e) => Console.WriteLine("button1.Click");

listBox.Items.Add(button1);

var button2 = new Button() { Content = "def" };
button2.Click += (s, e) => Console.WriteLine("button2.Click");

listBox.Items.Add(button2);

ContentPanel.Children.Add(listBox);

改为:

ContentPanel.Children.Add(
    new ListBox()
        ..Width = 200
        ..MouseEnter += ((s, e) => Console.WriteLine("MouseEnter"))
        ..Items.Add(
            new Button()
                ..Content = "abc";
                ..Click += ((s, e) => Console.WriteLine("button 1 Click")))
        ..Items.Add(
            new Button()
                ..Content = "def";
                ..Click += (s, e) => (Console.WriteLine("button 2 Click"))));

我的问题是,有没有办法模拟或近似接近C#中的方法级联？

这是我提出的一种方法.鉴于此扩展方法:

public static T Call<T>(this T obj, Action<T> proc)
{
    proc(obj);

    return obj;
}

上面的例子可以写成如下:

ContentPanel.Children.Add(
    new ListBox().Call(o => {
            o.Width = 200;
            o.MouseEnter += (s, e) => Console.WriteLine("MouseEnter");
            o.Items.Add(
                new Button().Call(b => {
                        b.Content = "abc";
                        b.Click += (s, e) => Console.WriteLine("button 1 Click"); }));
            o.Items.Add(
                new Button().Call(b => {
                    b.Content = "def";
                    b.Click += (s, e) => Console.WriteLine("button 2 Click"); })); }));

我不认为这很漂亮.:-)但它确实能够应用流畅的风格.

Answer 1

我认为您可以通过使用流畅的界面来接近您想要实现的目标。它将允许您链接方法以在一条语句中创建和初始化对象。

你可以得到类似的东西：

Fluent fluent = new Fluent();
var panel = fluent.CreateControlPanel().Children()
                .AddListBox().SetWidth(200).AddMouseEnterEvent((s, e) => { }).Create()
                .AddTextBox().SetText("Foo").Create()
                .GetControlPanel();

这个想法是一个方法返回一个对象，允许初始化另一个对象。初始化器链可以在任何项上调用“终结器”方法（上图Create），该方法返回原始对象（上图Children）以继续添加其他对象或配置初始对象。

例如， inAddListBox返回一个类型的对象ListBoxSetup，该对象具有一堆类似SetWidthor 的方法AddMouseEnterEvent。在这种情况下，Children也将是一个特殊的对象（例如类型ChildSetup），它具有一堆方法，例如AddListBox或AddTextBox。每个方法都负责创建一个类型的对象ListBox或TextBox设置要创建的底层对象的属性。Fluent将有一个方法可以正确设置返回整个对象结构。

看一下这个链接： http://blog.raffaeu.com/archive/2010/06/26/how-to-write- Fluent-interface-with-c-and-lambda.aspx

下面是为实现上述内容而创建的底层代码的示例。当然，代码的架构可以大大改进，但这里只是为了示例。

public class Fluent
{
    public ControlPanelCreator CreateControlPanel()
    {
        return new ControlPanelCreator(new StackPanel(), this);
    }
}

public class ControlPanelCreator
{
    #region Fields
    private Fluent fluent;
    private Panel panel;
    #endregion

    #region Constructors
    internal ControlPanelCreator(Panel panel, Fluent fluent)
    {
        this.fluent = fluent;
        this.panel = panel;
    }
    #endregion

    #region Methods
    public ControlPanelChildrenCreator Children()
    {
        return new ControlPanelChildrenCreator(this.panel, this);
    }
    #endregion
}

public class ControlPanelChildrenCreator
{
    #region Fields
    private ControlPanelCreator panelCreator;
    private Panel panel;
    #endregion

    #region Constructors
    internal ControlPanelChildrenCreator(Panel panel, ControlPanelCreator panelCreator)
    {
        this.panel = panel;
        this.panelCreator = panelCreator;
    }
    #endregion

    #region Methods
    public ListBoxCreator AddListBox()
    {
        ListBox listBox = new ListBox();
        this.panel.Children.Add(listBox);
        return new ListBoxCreator(listBox, this);
    }

    public TextBoxCreator AddTextBox()
    {
        TextBox textBox = new TextBox();
        this.panel.Children.Add(textBox);
        return new TextBoxCreator(textBox, this);
    }

    public Panel GetControlPanel()
    {
        return this.panel;
    }
    #endregion
}

public class ListBoxCreator
{
    #region Fields
    private ListBox listbox;
    private ControlPanelChildrenCreator parentCreator;
    #endregion

    #region Constructors
    internal ListBoxCreator(ListBox listBox, ControlPanelChildrenCreator parentCreator)
    {
        this.listbox = listBox;
        this.parentCreator = parentCreator;
    }
    #endregion

    #region Methods
    public ListBoxCreator SetWidth(int width)
    {
        this.listbox.Width = width;
        return this;
    }

    public ListBoxCreator AddMouseEnterEvent(Action<object, MouseEventArgs> action)
    {
        this.listbox.MouseEnter += new MouseEventHandler(action);
        return this;
    }

    public ControlPanelChildrenCreator Create()
    {
        return this.parentCreator;
    }
    #endregion
}

public class TextBoxCreator
{
    #region Fields
    private TextBox textBox;
    private ControlPanelChildrenCreator parentCreator;
    #endregion

    #region Constructors
    internal TextBoxCreator(TextBox textBox, ControlPanelChildrenCreator parentCreator)
    {
        this.textBox = textBox;
        this.parentCreator = parentCreator;
    }
    #endregion

    #region Methods
    public TextBoxCreator SetText(string defaultText)
    {
        this.textBox.Text = defaultText;
        return this;
    }

    public ControlPanelChildrenCreator Create()
    {
        return this.parentCreator;
    }
    #endregion
}