为什么在事件处理程序和LT没有限制; TEventArgs&GT ;? [英] Why no constraint on EventHandler<TEventArgs>?

问题描述

我只是偶然（当编译的东西，我没有想到会编译）想通了，事件处理程序是的不可以约束类型System.EventArgs。

I just figured out by accident (when something compiled that I didn't think would compile) that EventHandler is not constrained to the type System.EventArgs.

下面是内联文档：

#region Assembly mscorlib.dll, v4.0.0.0
// C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.5\mscorlib.dll
#endregion

namespace System
{
    // Summary:
    //     Represents the method that will handle an event.
    //
    // Parameters:
    //   sender:
    //     The source of the event.
    //
    //   e:
    //     An System.EventArgs that contains the event data.
    //
    // Type parameters:
    //   TEventArgs:
    //     The type of the event data generated by the event.
    [Serializable]
    public delegate void EventHandler<TEventArgs>(object sender, TEventArgs e);
}

这是文档和实现之间的不匹配？

Is this a mismatch between docs and implementation?

的我这么问是因为我很好奇。这不是一个不满意的地方。的

推荐答案

在.NET 4.5中除去类型约束。

The type constraint was removed in .net 4.5.

下面是.NET 4.5签名。
http://msdn.microsoft.com/en-美国/库/ db0etb8x％28V = vs.110％29.aspx

Here is the .net 4.5 signature. http://msdn.microsoft.com/en-us/library/db0etb8x%28v=vs.110%29.aspx

[SerializableAttribute]
public delegate void EventHandler<TEventArgs>(
    Object sender,
    TEventArgs e
)

下面是.NET 4.0签名。
http://msdn.microsoft.com/en-美国/库/ db0etb8x％28V = VS.100％29.aspx

Here is the .net 4.0 signature. http://msdn.microsoft.com/en-us/library/db0etb8x%28v=vs.100%29.aspx

[SerializableAttribute]
public delegate void EventHandler<TEventArgs>(
    Object sender,
    TEventArgs e
)
where TEventArgs : EventArgs

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