Option Strict On 不允许缩小方法和委托之间的隐式类型转换

Question

错误：Option Strict On 不允许缩小方法 'context_beginRequest<ByVal sender As Object, ByVal e As WindowsAuthenticationEventArgs>' 和委托 '<BeginRequest>' 之间的隐式类型转换

代码：

Public Sub Init(ByVal context As System.Web.HttpApplication) Implements System.Web.IHttpModule.Init
    'context.
    AddHandler context.BeginRequest, New EventHandler(AddressOf context_BeginRequest)
End Sub

context_BeginRequest 函数::

Public Sub context_BeginRequest(ByVal sender As Object, ByVal e As WindowsAuthenticationEventArgs)
.....

..... 结束子

Answer 1

这是因为HttpApplication.BeginRequest 只是EventHandler 类型...所以你的第二个参数应该是EventArgs 类型，而不是WindowsAuthenticationEventArgs。