Compiling and running code at runtime in .NET Core 1.0

Question

Is it possible to compile and run C# code at runtime in the new .NET Core (better .NET Standard Platform)?

I have seen some examples (.NET Framework), but they used NuGet packages that are not compatible with netcoreapp1.0 (.NETCoreApp,Version=v1.0)

Answer 1

Option #1: Use the full C# compiler to compile an assembly, load it and then execute a method from it.

This requires the following packages as dependencies in your project.json:

"Microsoft.CodeAnalysis.CSharp": "1.3.0-beta1-20160429-01",
"System.Runtime.Loader": "4.0.0-rc2-24027",

Then you can use code like this:

var compilation = CSharpCompilation.Create("a")
    .WithOptions(new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary))
    .AddReferences(
        MetadataReference.CreateFromFile(typeof(object).GetTypeInfo().Assembly.Location))
    .AddSyntaxTrees(CSharpSyntaxTree.ParseText(
        @"
using System;

public static class C
{
    public static void M()
    {
        Console.WriteLine(""Hello Roslyn."");
    }
}"));

var fileName = "a.dll";

compilation.Emit(fileName);

var a = AssemblyLoadContext.Default.LoadFromAssemblyPath(Path.GetFullPath(fileName));

a.GetType("C").GetMethod("M").Invoke(null, null);

Option #2: Use Roslyn Scripting. This will result in much simpler code, but it currently requires more setup:

• Create NuGet.config to get packages from the Roslyn nightly feed:

    <?xml version="1.0" encoding="utf-8"?>
    <configuration>
      <packageSources>
        <add key="Roslyn Nightly" value="https://www.myget.org/F/roslyn-nightly/api/v3/index.json" />
      </packageSources>
    </configuration>
  

• Add the following package as a dependency to project.json (notice that this is package from today. You will need different version in the future):

    "Microsoft.CodeAnalysis.CSharp.Scripting": "1.3.0-beta1-20160530-01",
  

  You also need to import dotnet (obsolete "Target Framework Moniker", which is nevertheless still used by Roslyn):

    "frameworks": {
      "netcoreapp1.0": {
        "imports": "dotnet5.6"
      }
    }
  

• Now you can finally use Scripting:

    CSharpScript.EvaluateAsync(@"using System;Console.WriteLine(""Hello Roslyn."");").Wait();