名称为“__o'不存在于当前上下文存在 [英] The name '__o' does not exist in the current context

问题描述

我刚安装了Visual Studio 2015年开业，我是工作在我的ASP .NET项目。我收到很多错误（全部完全相同），如下​​：

I just installed Visual Studio 2015 and opened my asp .net project that I was working on. I'm receiving many errors (all exactly the same) as below:

错误CS0103名称'__o'不在当前存在背景

Error CS0103 The name '__o' does not exist in the current context

嗯，事实上我没有任何变量命名__o和代码工作就像一个魅力（错误是无效的），但什么麻烦事了我的是，我无法看到，因为它去的地方在此列表中，我应该检查整个列表时，我的代码真的有一个错误。

Well actually I don't have any variables named __o and the code works like a charm (error is invalid) but what bothers me is that I'm not able to see when my code really has a error as it goes somewhere in this list and I should check the whole list.

的

推荐答案

我发现，如果我选择的只建而不是构建+智能感知的错误（涉及智能感知）会自行消失。

I found out that if I choose Build Only instead of Build + IntelliSense the errors (that are related to intellisense) will go away.

更新1：原因

这是发生这种情况的原因是，像这样的代码：

The reason that this is happening is that for codes like this:

<% if (true) { %>
    <%=1%>
<% } %>
<%=2%>

在以上述<提供智能感知;％=％>在设计时块，ASP.NET生成分配到一个临时变量__o和语言（VB或C＃），然后提供该变量的智能感知。 ％= ...％>块;当页面编译器看到的第一个<做到这一点。但在这里，块内，如果，所以以后如果关闭，该变量超出范围。我们最终会产生这样的：

In order to provide intellisense in <%= %> blocks at design time, ASP.NET generates assignment to a temporary __o variable and language (VB or C#) then provide the intellisense for the variable. That is done when page compiler sees the first <%= ... %> block. But here, the block is inside the if, so after the if closes, the variable goes out of scope. We end up generating something like this:

if (true) { 
    object @__o;
    @__o = 1;
}
@__o = 2;

解决方法是在网页中添加早期的虚拟表达。例如。 <％=％>。这不会呈现任何东西，它会确保__o声明中Render方法顶尖水平，如果有可能的（或其他作用域）语句之前。

The workaround is to add a dummy expression early in the page. E.g. <%="" %>. This will not render anything, and it will make sure that __o is declared top level in the Render method, before any potential if (or other scoping) statement.

更新2：摆脱这种错误而不失去其他智能感知错误

点击过滤器上的按钮上的错误列表面板，并取消选中的左上角在 CS0103 这对于错误代码：名称'__o'不在当前情况下存在并这些错误不会再显示，你还可以有其他的智能感知错误和警告：

Click on the filter button on the top left corner of the error list panel and uncheck the CS0103 which the error code for the: The name '__o' does not exist in the current context and these errors will not be shown anymore and you can still have other intelliSense errors and warnings:

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