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我修改了昨天发布的新版 Roslyn 的示例，使用了动态对象和 ExpandObject，但是我得到了一个编译器错误，我不知道如何修复。错误是:

(7,21) : error CS0656: 缺少编译器所需的成员‘ Microsoft.CSharp. RuntimeBinder.CSharpArgumentInfo. Create’

你能不能在新的编译器中使用动力学？我该怎么补救？下面是我更新的例子:

[TestMethod]
public void EndToEndCompileAndRun()
{
var text = @"using System.Dynamic;
public class Calculator
{
public static object Evaluate()
{
dynamic x = new ExpandoObject();
x.Result = 42;
return x.Result;
}
}";


var tree = SyntaxFactory.ParseSyntaxTree(text);
var compilation = CSharpCompilation.Create(
"calc.dll",
options: new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary),
syntaxTrees: new[] {tree},
references: new[] {new MetadataFileReference(typeof (object).Assembly.Location), new MetadataFileReference(typeof (ExpandoObject).Assembly.Location)});


Assembly compiledAssembly;
using (var stream = new MemoryStream())
{
var compileResult = compilation.Emit(stream);
compiledAssembly = Assembly.Load(stream.GetBuffer());
}


Type calculator = compiledAssembly.GetType("Calculator");
MethodInfo evaluate = calculator.GetMethod("Evaluate");
string answer = evaluate.Invoke(null, null).ToString();


Assert.AreEqual("42", answer);
}
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最佳答案

I think that you should reference the Microsoft.CSharp.dll assembly

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You may also want to check the properties of all your project references. Make sure any reference is using .NET newer than 2.0. I have a project that was referencing another project in the same solution and had to rebuild the dependency using a newer .NET framework target.

See this post.

Also, don't forget to add the Microsoft.CSharp reference to you main project like @Alberto said.

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ASP.NET MVC specific:

You can get this error in an MVC 6 controller if you forget to put [FromBody] in a POST method.

    [HttpPost("[action]")]
public void RunReport([FromBody]dynamic report)
{
...
}

The .NETCore default project already includes Microsoft.CSharp reference but you get pretty much the same message.

With [FromBody] added you can now post JSON and then just dynamically access the properties :-)

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To make the code work in .Net Core 2.1 I had to add this references in the compilation:

var compilation = CSharpCompilation.Create(
"calc.dll",
options: new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary),
syntaxTrees: new[] {tree},
references: new[] {
MetadataReference.CreateFromFile(typeof(object).Assembly.Location),
MetadataReference.CreateFromFile(typeof(ExpandoObject).Assembly.Location),
MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName("Microsoft.CSharp")).Location),
MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName("netstandard")).Location),
MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName("mscorlib")).Location),
MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName("System.Runtime")).Location),
}
);
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If your project is targeting .Net Core or .Net Standard, then instead of adding reference you can install the Microsoft.CSharp NuGet package to solve this error.


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