C# .NET reactive-programming system.reactive

反应式框架你好世界

发布于 2024-09-08 21:48:18 字数 816 浏览 5 评论 0原文

这是一个介绍反应式框架的简单程序。但我想尝试错误处理程序，将程序修改为：

var cookiePieces = Observable.Range(1, 10);
cookiePieces.Subscribe(x =>
   {
      Console.WriteLine("{0}! {0} pieces of cookie!", x);
      throw new Exception();  // newly added by myself
   },
      ex => Console.WriteLine("the exception message..."),
      () => Console.WriteLine("Ah! Ah! Ah! Ah!"));
Console.ReadLine();

在本示例中，使用了以下重载。

public static IDisposable Subscribe<TSource>(
     this IObservable<TSource> source, 
     Action<TSource> onNext, 
     Action<Exception> onError, 
     Action onCompleted);

我希望能看到打印的异常消息，但控制台应用程序崩溃了。原因是什么？

原文

This is an easy program to introduce the Reactive Framework. But I want to try the error handler, by modifying the program to be:

var cookiePieces = Observable.Range(1, 10);
cookiePieces.Subscribe(x =>
   {
      Console.WriteLine("{0}! {0} pieces of cookie!", x);
      throw new Exception();  // newly added by myself
   },
      ex => Console.WriteLine("the exception message..."),
      () => Console.WriteLine("Ah! Ah! Ah! Ah!"));
Console.ReadLine();

In this sample the follwing overload is used.

public static IDisposable Subscribe<TSource>(
     this IObservable<TSource> source, 
     Action<TSource> onNext, 
     Action<Exception> onError, 
     Action onCompleted);

I hoped I would see the exception message printed, but the console application crashed. What is the reason?

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晨敛清荷 2024-09-15 21:48:18

异常处理程序用于处理可观察对象本身创建的异常，而不是由观察者创建的异常。

引发异常处理程序的一种简单方法如下所示：

using System;
using System.Linq;

class Test
{
    static void Main(string[] args)
    {
        var xs = Observable.Range(1, 10)
                           .Select(x => 10 / (5 - x));

        xs.Subscribe(x => Console.WriteLine("Received {0}", x),
                     ex => Console.WriteLine("Bang! {0}", ex),
                     () => Console.WriteLine("Done"));

        Console.WriteLine("App ending normally");
    }
}

输出：

Received 2
Received 3
Received 5
Received 10
Bang! System.DivideByZeroException: Attempted to divide by zero.
   at Test.<Main>b__0(Int32 x)
   at System.Linq.Observable.<>c__DisplayClass35a`2.<>c__DisplayClass35c.<Select
>b__359(TSource x)
App ending normally

The exception handler is used for exceptions created in the observable itself, not by the observer.

An easy way to provoke the exception handler is something like this:

using System;
using System.Linq;

class Test
{
    static void Main(string[] args)
    {
        var xs = Observable.Range(1, 10)
                           .Select(x => 10 / (5 - x));

        xs.Subscribe(x => Console.WriteLine("Received {0}", x),
                     ex => Console.WriteLine("Bang! {0}", ex),
                     () => Console.WriteLine("Done"));

        Console.WriteLine("App ending normally");
    }
}

Output:

Received 2
Received 3
Received 5
Received 10
Bang! System.DivideByZeroException: Attempted to divide by zero.
   at Test.<Main>b__0(Int32 x)
   at System.Linq.Observable.<>c__DisplayClass35a`2.<>c__DisplayClass35c.<Select
>b__359(TSource x)
App ending normally

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