c# - 如何传入特定类的方法名作为另一个方法的参数

Question

我正在尝试编写一个 C# 方法，该方法通过传入一个对象并运行其方法之一来生成线程。

这是一个过于简单的例子:

class ThreadData {
    private JObject jsonObj;
    private int start;
    private int end;
    public ThreadData(JObject jsonObj, int start, int end) {
        this.jsonObj= jsonObj;
        this.start = start;
        this.end = end;
    }
    public void Calculate() {
        for (int i = start; i < end; i++) {
            // do stuff
        }
    }
    public void Produce() {
        for (int i = start; i < end; i++) {
            // do other stuff
        }
    }
}

class Program {
    static void Main(string[] args) {
        JObject jsonObj= SomeRestAPICall();
        RunInThreads(5, jsonObj, Calculate);
        RunInThreads(5, jsonObj, Produce);
    }

    // ...
}

json 对象有 n 个项目。 RunInThreads 方法的目标是生成 X 个线程，将 jsonObj 分成相等的 X 个 block ，并让每个线程在每个 block 上运行。我将线程数、json 对象以及运行 ThreadData 类的方法传递给该方法。

private static void RunInThreads(int numOfThreads, JObject object, type functionToRun) {
    int chunks = object.Count() / numOfThreads;
    List<Thread> threads = new List<Thread>();
    for (int i = 1; i <= numOfThreads; i++) {
        int start = (i - 1) * chunks;
        int end = i == numOfThreads? object.Count() : start + chunks;

        ThreadData threadData = new ThreadData(object, start, end);
        Thread thread = new Thread(new ThreadStart(threadData.<FUNCTION>));
        thread.Start();
        threads.Add(thread);
    }
    foreach (Thread t in threads) { t.Join(); }
}

我不太明白如何将函数名作为参数传入。我会使用委托(delegate)吗？如果我使用两种不同的方法，我会在每个方法中输入自定义方法名称。例如，对于 Calculate() 方法，它将是这样的:

private static void CalculateInThreads(int numOfThreads, JObject object) {
    int chunks = object.Count() / numOfThreads;
    List<Thread> threads = new List<Thread>();
    for (int i = 1; i <= numOfThreads; i++) {
        int start = (i - 1) * chunks;
        int end = i == numOfThreads? object.Count() : start + chunks;

        ThreadData threadData = new ThreadData(object);
        Thread thread = new Thread(new ThreadStart(threadData.functionToRun));
        thread.Start();
        threads.Add(thread);
    }
    foreach (Thread t in threads) { t.Join(); }
}

Answer 1

我相信这样的事情会奏效:

private static void RunInThreads(int numOfThreads, JObject object, 
                                 Action<ThreadData> functionToRun) {
    int chunks = object.Count() / numOfThreads;
    List<Thread> threads = new List<Thread>();
    for (int i = 1; i <= numOfThreads; i++) {
        int start = (i - 1) * chunks;
        int end = i == numOfThreads? object.Count() : start + chunks;

        ThreadData threadData = new ThreadData(object, start, end);
        Thread thread = new Thread(new ThreadStart(() => functionToRun(threadData));
        thread.Start();
        threads.Add(thread);
    }
    foreach (Thread t in threads) { t.Join(); }
}

你会这样调用它:

RunInThreads(5, jsonObj, t=>t.Calculate());

语法解释:

Action<ThreadData>是一个 Action<T> - 一个预定义委托(delegate)，接受一个输入参数并返回 void。

t => t.Calculate()语法是 lambda expression表示委托(delegate)的一个实例 - 它基本上是定义一个采用单个参数的内联函数的简短方法 t . t 的类型推断为 ThreadData因为编译器知道委托(delegate)是一个 Action<ThreadData> .

你可以像这样用更多的按键来写同样的东西:

void DoCalculate(ThreadData data)
{
    data.Calculate();
}
...
RunInThread(5, jsonObj, new Action<ThreadData>(DoCalculate));