问题描述
我的任务是对 2009 年开发的 Web 应用程序进行现代化改造.它是用 VB.NET 编写的，并使用 ASP.NET WebForms.我想在 VB.NET 中使用最新的语言结构.
我得到了有用的提示，说Visual Basic 10.0 不允许字符串插值"，这是我尝试使用的，但我未能找到提高语言水平的方法.
我在这个相关问题中有提示
或者，绕过上述 GUI 功能，直接进入 Nuget 包管理器，将以下包的最新版本安装到项目/站点中，以便与 VB.NET 语言保持同步可能是:
- Microsoft.CodeDom.Providers.DotNetCompilerPlatform
- Microsoft.Net.Compilers
(NB 最新版本 要求 .NET 4.6+ 是安装系统上供编译器运行，但可以编译针对任何平台的代码.
这很可能会让您为 C# 6/VB 14 排序.获得 VB 15 的最后一步是:编辑 web.config 文件中的 langversion，使其读取为 15.0(或 latest 如果你想使用最新版本 - 这是我的首选).
<编译器><编译器语言=vb;vbs;visualbasic;vbscript"扩展=.vb"type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.VBCodeProvider，Microsoft.CodeDom.Providers.DotNetCompilerPlatform，版本=1.0.8.0，文化=中性，PublicKeyToken=31bf3856ad364e35"warningLevel="4" compilerOptions="/langversion:15.0/nowarn:41008/define:_MYTYPE="Web"/optionInfer+"/></编译器> 不幸的是，在将我的 Roslyn 升级到 C# 7.0 和 7.1 之后，我发现自己不得不编辑 langversion，所以这绝对是值得关注的事情.
顺便说一句，这个答案不仅仅适用于旧项目——如果使用的模板不引用 Nuget 编译器包，即使在 VS 2017 中创建的新 Web 项目也需要这个修复.Roslyn 不是强制性的，例如模板据报道，新网站尚未更新.
I've been tasked with modernising a web application developed in 2009. It is written in VB.NET and using ASP.NET WebForms. I would like to use the latest language constructs in VB.NET.
I get helpful pointers saying "Visual Basic 10.0 does not allow string interpolation", which was what I was trying to use, but I failed to find a way to raise the language level.
I have the tips in this related question How to change the VB.NET language version in Visual Studio 2015, but they did not help in this context.
In ReSharper properties, I could set the "VB Language Level" for each of the four different projects to "Visual Basic .NET 15". This changes a line of XML in the project's .DotSetting file, and this setting changes how ReSharper analyzes the code, but alas, this did not take away the compilation errors.
How do I enable support in Visual Studio 2017 for the latest version of VB.NET in an ASP.NET Web Site or Web Application project?
To use the latest VB.NET or C# with ASP.NET Web Applications and Web Sites projects you need to install or update two Rosyln Nuget packages.
Microsoft:
When you have a solution open which has at least one web project which is targetting .NET 4.5+ and does not have the DotNetCompilerPlatform NuGet package in the Project menu you’ll see a new option, Enable C# 6 / VB 14 appear.
The following screenshot is from VS2015 but the option should be present in VS2017 too:
Alternatively, bypass the above GUI feature and just go directly to the Nuget package manager and install the latest version of the following packages into the project/site to be as up-to-date with the VB.NET language as it is possible to be:
- Microsoft.CodeDom.Providers.DotNetCompilerPlatform
- Microsoft.Net.Compilers
(NB The latest releases are demanding .NET 4.6+ is installed on the system for the compiler to run, but can compile code targeting any platform).
This will likely get you sorted for C# 6/VB 14. There is one last step to get VB 15: edit the langversion in the web.config file so that it reads 15.0 (or latest if you want to be on the newest version - this in my preferred option).
<system.codedom>
<compilers>
<compiler language="vb;vbs;visualbasic;vbscript" extension=".vb"
type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.VBCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.8.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"
warningLevel="4" compilerOptions="/langversion:15.0 /nowarn:41008 /define:_MYTYPE="Web" /optionInfer+"/>
</compilers>
Unfortunately I have found myself having to edit the langversion after upgrading my Roslyn to C# 7.0 and then to 7.1 so it is definitely something to look out for.
By the way, this answer doesn't just apply to old projects - even new web projects created in VS 2017 need this fix if the template used doesn't reference the Nuget compiler packages. Roslyn is not mandatory and the template for e.g. a new Web Site has reportedly not been updated.
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