含义与Action和Func参数 [英] Ambiguity with Action and Func parameter

问题描述

如何可能这个代码

TaskManager.RunSynchronously<MyObject>(fileMananager.BackupItems, package);

导致编译错误

The call is ambiguous between the following methods or properties:
'TaskManager.RunSynchronously<MyObject>(System.Action<MyObject>, MyObject)' and
'TaskManager.RunSynchronously<MyObject>(System.Func<MyObject, bool>, MyObject)'

public void BackupItems(MyObject package)

和ambiguous方法是

and "ambiguous" methods are

static class TaskManager
{
    public static void RunSynchronously<TInput>(Action<TInput> task, TInput param)
    {
        Task.Factory.StartNew(() => task(param));
    }

    public static bool RunSynchronously<TInput>(Func<TInput, bool> task, TInput param)
    {
        return Task.Factory.StartNew(() => task(param)).Result;
    }
}

在我看来，这些方法。我在这里缺少什么？

It seems to me that there is an ample difference between these methods. What am I missing here?

编辑：

除了接受的答案刚刚遇到一个类似问题的解决方案。以下是链接。

Besides the accepted answer I just came across a solution in a similar question. Here is the link.

推荐答案

原因是方法的返回类型不是其签名的一部分。因此，在解决正确的重载时，编译器仅查看方法的参数。

The reason is that the return type of a method is not part of its signature. Thus, while resolving the correct overload, the compiler only looks at the parameter of the method.

最简单的解决方案是简单地不使用隐式方法组转换。所有以下编译：

The easiest solution is to simply not use the implicit method group conversion. All of the following compile:

TaskManager.RunSynchronously<MyObject>(
    x => fileMananager.BackupItems(x), package);

TaskManager.RunSynchronously<MyObject>(
    (Action<MyObject>)fileMananager.BackupItems, package);

TaskManager.RunSynchronously<MyObject>(
    new Action<MyObject>(fileMananager.BackupItems), package);

第一个是最优雅的，但它也是唯一一个 - 轻微的 - 运行时性能影响，因为额外的重定向。但是，这种影响是如此之小，您实际上不应该在乎。

The first one is the most elegant of them, but it also is the only one with a - slight - runtime performance impact, because of an additional redirection. However, this impact is so small that you actually shouldn't care.

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