为什么不编译多次使用PreApplicationStartMethodAttribute? [英] Why multiple using of PreApplicationStartMethodAttribute isn't compiled?

问题描述

System.Web.PreApplicationStartMethodAttribute定义为:

System.Web.PreApplicationStartMethodAttribute defined as:

[AttributeUsage(AttributeTargets.Assembly, AllowMultiple=true)]
public sealed class PreApplicationStartMethodAttribute : Attribute 
{}

即它允许多次使用(AllowMultiple = true). 但是，如果我尝试将这个属性的几种用法添加到我的程序集中:

I.e. it allows multiple usage (AllowMultiple=true). But if I try to added several usages of this attribute to my assembly :

[assembly: PreApplicationStartMethod(typeof(MyType1), "Start")]
[assembly: PreApplicationStartMethod(typeof(MyType2), "Start")]

我收到编译器错误:

错误2复制了'PreApplicationStartMethod'属性

Error 2 Duplicate 'PreApplicationStartMethod' attribute

这是为什么?

推荐答案

我怀疑您正在查看

I suspect you were looking at the .NET 4.5 version, which is documented as having AllowMultiple = True.

.NET 4.0版本的文档将其显示为:

The documentation for the .NET 4.0 version shows it as AllowMultiple = false:

[AttributeUsageAttribute(AttributeTargets.Assembly, AllowMultiple = false)]
public sealed class PreApplicationStartMethodAttribute : Attribute

因此，如果您以.NET 4.5为目标，那应该没问题.

So if you target .NET 4.5, it should be okay.

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