为什么对 EventHandler<TEventArgs> 没有约束?

问题描述

我只是偶然发现(当编译的东西我认为不会编译时)EventHandler 不限制为 System.EventArgs 类型.

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.

这是内联文档:

#region Assembly mscorlib.dll, v4.0.0.0
// C:Program Files (x86)Reference AssembliesMicrosoftFramework.NETFrameworkv4.5mscorlib.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吗?

Is this a mismatch between docs and implementation?

我问是因为我很好奇.这根本不是抱怨.

推荐答案

.net 4.5 中删除了类型约束.

The type constraint was removed in .net 4.5.

这是 .net 4.5 签名.http://msdn.microsoft.com/en-us/library/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
)

这是 .net 4.0 签名.http://msdn.microsoft.com/en-us/library/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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