blocks|key|3716662|text|有问题的对象将需要实现您提供的接口。将接口作为参数，然后就可以调用该接口公开的任何方法。否则，您将无法知道对象的功能。或者，您可以将委托作为参数并调用它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3716663|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

The object in question will need to implement an interface provided by you. Take the interface as a parameter, and then you can call any method that the interface exposes. Otherwise you have no way of knowing what the object is capable of. That, or you could take a delegate as a parameter and call that.

blocks|key|1109212|text|对于委托来说，这听起来是一个完美的方法--特别是，带有委托的回调正是在.NET中异步模式中处理委托的方式。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1109213|调用者通常会向你传递一些状态和一个委托，你将它们都存储在你已经获得的任何上下文中，然后调用传递给它状态和任何你可能得到的结果的委托。|1109214|您可以将状态设置为object，也可以使用泛型委托并获取适当类型的状态，例如|offset|length|style|CODE|1109215|public+delegate+void+Callback<T>(T+state,+OperationResult+result)|code-block|syntax|javascript|1109216|然后：|1109217|public+void+DoSomeOperation(int+otherParameterForWhateverReason,
++++++++++++++++++++++++++++Callback<T>+callback,+T+state)|1109218|当您使用.NET+3.5时，您可能希望使用现有的Func<...>和Action<...>委托类型，但您可能会发现声明自己的委托类型会更清晰。(名称可能会让你更清楚地知道它是做什么用的。)|1109219|entityMap^0|0|0|9|6|0|0|0|0|O|9|Y|B|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Y|8|@$F|Z|G|10|H|I]]|9|@]|A|$]]|$1|J|3|K|5|L|7|11|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|12|8|@]|9|@]|A|$]]|$1|Q|3|R|5|L|7|13|8|@]|9|@]|A|$M|N]]|$1|S|3|T|5|6|7|14|8|@$F|15|G|16|H|I]|$F|17|G|18|H|I]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|V|$]]

Sounds like a perfect recipe for delegates - in particular, callbacks with delegates are exactly how this is handled in the asynchronous pattern in .NET.

The caller would usually pass you some state and a delegate, and you store both of them in whatever context you've got, then call the delegate passing it the state and whatever result you might have.

You could either make the state just <code>object</code> or potentially use a generic delegate and take state of the appropriate type, e.g.

<pre><code>public delegate void Callback&lt;T&gt;(T state, OperationResult result)
</code></pre>

Then:

<pre><code>public void DoSomeOperation(int otherParameterForWhateverReason,
 Callback&lt;T&gt; callback, T state)
</code></pre>

As you're using .NET 3.5 you might want to use the existing <code>Func&lt;...&gt;</code> and <code>Action&lt;...&gt;</code>
delegate types, but you may find it makes it clearer to declare your own. (The name may make it clearer what you're using it for.)

blocks|key|1114717|text|有没有理由不让你的库提供一个在操作完成时触发的公共事件？然后调用者只需注册来处理事件，您就不必担心传递对象或委托。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1114718|实现您提供的接口的对象可以工作，但它似乎更像是Java方法，而不是.NET方法。在我看来，事件似乎更清晰一些。|1114719|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Is there a reason not to have your library provide a public event to be fired when the operation is complete? Then the caller could just register to handle the event and you don't have to worry about passing around objects or delegates.

The object implementing an interface you have provided would work, but it seems to be more the Java approach than the .NET approach. Events seem a bit cleaner to me.

blocks|key|4562072|text|为您提供两个选项：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4562073|4562074|让函数接受delegate+(Action表示不返回任何内容的回调，Func表示返回任何内容的回调)，并在调用时使用匿名委托或Lambda表达式。|ordered-list-item|offset|length|style|CODE|4562075|使用接口|4562076|4562077|使用委托/lambda|4562078|public+static+void+DoWork(Action+processAction)
{
++//+do+work
++if+(processAction+!=+null)
++++processAction();
}

public+static+void+Main()
{
++//+using+anonymous+delegate
++DoWork(delegate()+{+Console.WriteLine("Completed");+});

++//+using+Lambda
++DoWork(()+=>+Console.WriteLine("Completed"));
}|code-block|syntax|javascript|4562079|如果你的回调需要传递一些东西给它，你可以在Action上使用一个类型参数|4562080|public+static+void+DoWork(Action<string>+processAction)
{
++//+do+work
++if+(processAction+!=+null)
++++processAction("this+is+the+string");
}

public+static+void+Main()
{
++//+using+anonymous+delegate
++DoWork(delegate(string+str)+{+Console.WriteLine(str);+});

++//+using+Lambda
++DoWork((str)+=>+Console.WriteLine(str));
}|4562081|如果它需要多个参数，您可以向Action添加更多类型参数。如果需要返回类型，请如前所述使用Func，并将返回类型作为最后一个类型参数(Func<string,+int>是一个接受字符串并返回整数的函数。)|4562082|有关委派here的更多信息。|4562083|4562084|public+interface+IObjectWithX
{
++void+X();
}

public+class+MyObjectWithX+:+IObjectWithX
{
++public+void+X()
++{
++++//+do+something
++}
}

public+class+ActionClass
{
++public+static+void+DoWork(IObjectWithX+handlerObject)
++{
++++//+do+work
++++handlerObject.X();
++}
}

public+static+void+Main()
{
++var+obj+=+new+MyObjectWithX()
++ActionClass.DoWork(obj);
}|4562085|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.microsoft.com/en-us/dotnet/api/system.delegate?view=netframework-4.8|1|https://docs.microsoft.com/en-us/dotnet/api/system.action-1?view=netframework-4.8|2|https://docs.microsoft.com/en-us/dotnet/api/system.func-2?view=netframework-4.8|3|https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/delegates/index?view=netframework-4.8^0|0|0|F|6|Y|4|5|8|0|F|6|1|Y|4|2|0|0|0|0|0|L|6|0|0|E|6|19|4|1V|H|0|4|4|3|0|0|0^^$0|@$1|2|3|4|5|6|7|1I|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|1J|8|@]|9|@]|A|$]]|$1|C|3|D|5|E|7|1K|8|@$F|1L|G|1M|H|I]|$F|1N|G|1O|H|I]]|9|@$F|1P|G|1Q|1|1R]|$F|1S|G|1T|1|1U]|$F|1V|G|1W|1|1X]]|A|$]]|$1|J|3|K|5|E|7|1Y|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|20|8|@]|9|@]|A|$]]|$1|O|3|P|5|Q|7|21|8|@]|9|@]|A|$R|S]]|$1|T|3|U|5|6|7|22|8|@$F|23|G|24|H|I]]|9|@]|A|$]]|$1|V|3|W|5|Q|7|25|8|@]|9|@]|A|$R|S]]|$1|X|3|Y|5|6|7|26|8|@$F|27|G|28|H|I]|$F|29|G|2A|H|I]|$F|2B|G|2C|H|I]]|9|@]|A|$]]|$1|Z|3|10|5|6|7|2D|8|@]|9|@$F|2E|G|2F|1|2G]]|A|$]]|$1|11|3|K|5|6|7|2H|8|@]|9|@]|A|$]]|$1|12|3|13|5|Q|7|2I|8|@]|9|@]|A|$R|S]]|$1|14|3|-4|5|6|7|2J|8|@]|9|@]|A|$]]]|15|$16|$5|17|18|19|A|$1A|1B]]|1C|$5|17|18|19|A|$1A|1D]]|1E|$5|17|18|19|A|$1A|1F]]|1G|$5|17|18|19|A|$1A|1H]]]]

Two options for you:

<ol>
<li>Have the function accept a <a href="https://docs.microsoft.com/en-us/dotnet/api/system.delegate?view=netframework-4.8" rel="nofollow noreferrer">delegate</a> (<a href="https://docs.microsoft.com/en-us/dotnet/api/system.action-1?view=netframework-4.8" rel="nofollow noreferrer"><code>Action</code></a> for a callback that doesn't return anything, <a href="https://docs.microsoft.com/en-us/dotnet/api/system.func-2?view=netframework-4.8" rel="nofollow noreferrer"><code>Func</code></a> for one that does) and use an anonymous delegate or Lambda Expression when calling it.</li>
<li>Use an interface</li>
</ol>

<h2>Using a delegate/lambda</h2>

<pre><code>public static void DoWork(Action processAction)
{
 // do work
 if (processAction != null)
 processAction();
}

public static void Main()
{
 // using anonymous delegate
 DoWork(delegate() { Console.WriteLine("Completed"); });

 // using Lambda
 DoWork(() =&gt; Console.WriteLine("Completed"));
}
</code></pre>

If your callback needs to have something passed to it, you can use a type parameter on <code>Action</code>:

<pre><code>public static void DoWork(Action&lt;string&gt; processAction)
{
 // do work
 if (processAction != null)
 processAction("this is the string");
}

public static void Main()
{
 // using anonymous delegate
 DoWork(delegate(string str) { Console.WriteLine(str); });

 // using Lambda
 DoWork((str) =&gt; Console.WriteLine(str));
}
</code></pre>

If it needs multiple arguments, you can add more type parameters to <code>Action</code>. If you need a return type, as mentioned use <code>Func</code> and make the return type the last type parameter (<code>Func&lt;string, int&gt;</code> is a function accepting a string and returning an int.)

More about delegates <a href="https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/delegates/index?view=netframework-4.8" rel="nofollow noreferrer">here</a>.

<h2>Using an interface</h2>

<pre><code>public interface IObjectWithX
{
 void X();
}

public class MyObjectWithX : IObjectWithX
{
 public void X()
 {
 // do something
 }
}

public class ActionClass
{
 public static void DoWork(IObjectWithX handlerObject)
 {
 // do work
 handlerObject.X();
 }
}

public static void Main()
{
 var obj = new MyObjectWithX()
 ActionClass.DoWork(obj);
}
</code></pre>

blocks|key|1109282|text|您可以使用C#.NET中提供的System.Action来实现回调函数。请查看此示例：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1109283|++++//Say+you+are+calling+some+FUNC1+that+has+the+tight+while+loop+and+you+need+to+
++++//get+updates+on+what+percentage+the+updates+have+been+done.
++++private+void+ExecuteUpdates()
++++{
++++++++Func1(Info+=>+{+lblUpdInfo.Text+=+Info;+});
++++}

++++//Now+Func1+would+keep+calling+back+the+Action+specified+in+the+argument
++++//This+System.Action+can+be+returned+for+any+type+by+passing+the+Type+as+the+template.
++++//This+example+is+returning+string.
++++private+void+Func1(System.Action<string>+UpdateInfo)
++++{
++++++++int+nCount+=+0;
++++++++while+(nCount+<+100)
++++++++{
++++++++++++nCount%2B%2B;
++++++++++++if+(UpdateInfo+!=+null)+UpdateInfo("Counter:+"+%2B+nCount.ToString());
++++++++++++//System.Threading.Thread.Sleep(1000);
++++++++}
++++}|code-block|syntax|javascript|1109284|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can use System.Action available in C#.NET for callback functions. Please check this sample example:

<pre><code> //Say you are calling some FUNC1 that has the tight while loop and you need to 
 //get updates on what percentage the updates have been done.
 private void ExecuteUpdates()
 {
 Func1(Info =&gt; { lblUpdInfo.Text = Info; });
 }

 //Now Func1 would keep calling back the Action specified in the argument
 //This System.Action can be returned for any type by passing the Type as the template.
 //This example is returning string.
 private void Func1(System.Action&lt;string&gt; UpdateInfo)
 {
 int nCount = 0;
 while (nCount &lt; 100)
 {
 nCount++;
 if (UpdateInfo != null) UpdateInfo("Counter: " + nCount.ToString());
 //System.Threading.Thread.Sleep(1000);
 }
 }
</code></pre>

I want to have a library that will have a function in it that accepts an object for it's parameter.

With this object I want to be able to call a specified function when X is finished. The function that will be called is to be specified by the caller, and X will be done and monitored by the library.

How can I do this?

For reference I'm using C# and .NET 3.5

Callbacks in C#

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我想有一个库，里面有一个函数，它接受一个对象作为它的参数。有了这个对象，当X完成时，我希望能够调用指定的函数。将被调用的函数将由调用者指定，X将由库完成和监视。我该怎么做呢？作为参考，我使用C#和.NET 3.5

问C#中的回调
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