存储带有参数的动作列表，然后执行它们

Question

我有一个操作的枚举，我想运行：

public enum theActions
{
    action1,
    action2
}

我想将它们存储在字典中：

public Dictionary<theActions, Action> _theActions { get; }

_theActions = new Dictionary<theActions, Action>
{
    [theActions.action1] = () => action1Func()
};

对于每个操作，我都有自己的功能：

public void action1Func(int inParam)
{
    //do whatever
}

稍后，我需要调用其中一个函数：

public void execAction(int inVar, Action action) 
{ 
    //inVar isn't the parameter I want to pass to the action. It's used, for something else.
    action(); 
}

execAction(1, _theActions[theActions.action1]);

我不确定，如何更改我的代码以使 Action 在任何地方都接受参数，如果我需要一个不需要参数的操作怎么办？我是否必须在该函数中添加一个虚拟参数？

我知道了，到目前为止：

using System;
using System.Collections.Generic;
using System.Windows.Forms;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        public enum theActions
        {
            action1,
            action2
        }

        public Dictionary<theActions, Action<int>> _theActions { get; }

        public void execAction(int inVar, Action<int> action)
        {
            //inVar isn't the parameter I want to pass to the action. It's used, for something else.
//            action();
        }

        public Form1()
        {
            InitializeComponent();

            _theActions = new Dictionary<theActions, Action<int>>
            {
                [theActions.action1] = (Action<int>)((int x) => action1Func(x))
            };

        }

        public void action1Func(int inParam)
        {
            //do whatever
            MessageBox.Show($"Hello ... inParam : {inParam}");
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //This works manually
            _theActions[theActions.action1].Invoke(12);

            //But, I want the execAction to work
            //execAction(1, _theActions[theActions.action1]);
        }
    }
}

它可以手动调用它。我只需要帮助进入 execAction() 并运行它。所以，关闭。

Answer 1

public void execAction(int someInt, Action action)
{
    action();

    // or: action.Invoke();
}

您应该能够在初始化中删除整个 lambda，因为您已经有一个带有一个 int 参数的方法：

public Form1()
{
    InitializeComponent();

    _theActions = new Dictionary<theActions, Action<int>>
    {
        [theActions.action1] = action1Func
    };
}

带有特定参数的调用如下所示：

int yourParameter = 12345;
execAction(42, () => (_theActions[theActions.action1]).Invoke(yourParameter));

Answer 2

尝试删除字典并改用它：

public void action1Func(int p1) //action 1 has one int parameter
{
}
public void action2Func() //let's consider action 2 takes no parameters
{
}
public void action3Func(int p1, int p2, int p3)
{
}
// Order of parameters was changed to leverage implicit null parameters for convenience
// See invocations below
public void execAction(theActions action, 
                       int? inVar1 = null, int? inVar2 = null, int? inVar3 = null) 
{
    switch (action) // Based on action kind, invoke the right function.
    {               // The mapping is now coded in a switch statement 
                    // instead of a Dictionary declaration
        case theActions.action1: action1Func(inVar1.Value); break;
        case theActions.action2: action2Func(); break;
        case theActions.action3: action3Func(inVar1.Value, inVar2.Value, inVar3.Value); break;
    }
}
// Invocations
execAction(theActions.action1, 1);
execAction(theActions.action2);
execAction(theActions.action3, 1, 3, 5);

如果对execAction正确使用隐式参数声明，则可以调用具有任意数量参数的方法。

您可以执行参数验证（例如，您可以在调用之前检查 inVar1.HasValue == true），否则如果省略参数，代码将快速失败（如果 HasValue 为 false，Nullable.Value 会抛出 InvalidOperationException）。

如果参数数量增加并且变得无法管理，您可以将它们放入参数包类中并通过构造函数验证它们的初始化。

如果您定义这些重载，您可以获得更高的安全性（编译时检查）：

public void execAction1(int p1)
    => execAction(theActions.action1, p1);
public void execAction2()
    => execAction(theActions.action2);
public void execAction3(int p1, int p2, int p3)
    => execAction(theActions.action3, p1, p2, p3);

// Invocations will be
execAction1(1);
execAction2();
execAction3(1, 3, 5);

但这最后一步有点违背了目的。您可以改为调用原始方法:)。