Loading an assembly generated by the Roslyn compiler

I have been adding Roslyn support to the O2 Plarform and here is how you can use its Roslyn support to compile (code), create (and assembly) and invoke (its method) one line of code:

return @"using System; class Greeter { static string Greet() {  return ""Another hello!!""; }}"
        .tree().compiler("Great").create_Assembly().type("Greeter").invokeStatic("Greet"); 

//O2Ref:O2_FluentSharp_Roslyn.dll

Here is a version that executes a code snippet that looks like yours (I added a return value):

panel.clear().add_ConsoleOut();
var code = @"
using System;
class Greeter
{
    static string Greet()
    { 
        Console.WriteLine(""Hello, World""); 
        return ""hello from here"";
    }
}";
var tree = code.astTree();
if (tree.hasErrors())
    return tree.errors();   

var compiler = tree.compiler("Great")
                   .add_Reference("mscorlib");

if (compiler.hasErrors()) 
    return compiler.errors();    

var assembly  =tree.compiler("Great")
                   .create_Assembly();

return assembly.type("Greeter")
               .invokeStatic("Greet"); 

//O2Ref:O2_FluentSharp_Roslyn.dll
//O2File:_Extra_methods_Roslyn_API.cs
//O2File:API_ConsoleOut.cs

For a couple more details and screenshots of what this looks like, see this blog post: 1 line to compile, create and execute: O2 Script to use Roslyn to Dynamically compile and execute a method

UPDATE: see http://blog.diniscruz.com/search/label/Roslyn for a large number number of Roslyn related posts and tools (created using the O2 Platform)

There is a new API for the References that looks like this:

var compilation = Compilation.Create(outputFile,
    syntaxTrees: new[] { syntaxTree },
    references: new[] {
        new MetadataFileReference(typeof(object).Assembly.Location),
        new MetadataFileReference(typeof(Enumerable).Assembly.Location),
    },
    options: new CompilationOptions(OutputKind.DynamicallyLinkedLibrary)
);

This is with the latest Roslyn-CTP 2012 in Sept...

This code worked beautifully:

using System;

using Roslyn.Compilers;
using Roslyn.Compilers.CSharp;

using System.IO;
using System.Reflection;
using System.Linq;

namespace LoadingAClass
{
    class Program
    {
        static void Main(string[] args)
        {
            var syntaxTree = SyntaxTree.ParseCompilationUnit(@"
using System;
namespace HelloWorld
{
    class Greeter
    {
        public static void Greet()
        {
            Console.WriteLine(""Hello, World"");
        }
    }
}");

            string dllPath = Path.Combine(Directory.GetCurrentDirectory(), "Greeter.dll");
            string pdbPath = Path.Combine(Directory.GetCurrentDirectory(), "Greeter.pdb");

            var compilation = Compilation.Create(dllPath,
                new CompilationOptions(
                    assemblyKind: AssemblyKind.DynamicallyLinkedLibrary
                ))
                .AddSyntaxTrees( syntaxTree )
                .AddReferences(new AssemblyFileReference(typeof(object).Assembly.Location))
                .AddReferences(new AssemblyFileReference(typeof(Enumerable).Assembly.Location));

            EmitResult result;

            using (FileStream dllStream = new FileStream(dllPath, FileMode.OpenOrCreate))
            using (FileStream pdbStream = new FileStream(pdbPath, FileMode.OpenOrCreate))
            {
                result = compilation.Emit(
                    executableStream: dllStream,
                    pdbFileName: pdbPath,
                    pdbStream: pdbStream);
            }

            if (result.Success)
            {
                //assembly = Assembly.LoadFile(Path.Combine(Directory.GetCurrentDirectory(), @"Greeter.dll"));
                Assembly assembly = Assembly.LoadFrom(@"Greeter.dll");

                Type type = assembly.GetType("HelloWorld.Greeter");
                var obj = Activator.CreateInstance(type);

                type.InvokeMember("Greet",
                    BindingFlags.Default | BindingFlags.InvokeMethod,
                    null,
                    obj,
                    null);
            }
            else
            {
                Console.WriteLine("No Go");
                Console.WriteLine(result.Diagnostics.ToString());
            }

            Console.WriteLine("<ENTER> to continue");
            Console.ReadLine();

        }
    }
    // Thanks, http://blogs.msdn.com/b/csharpfaq/archive/2011/11/23/using-the-roslyn-symbol-api.aspx
    // Thanks, http://social.msdn.microsoft.com/Forums/en-US/roslyn/thread/d620a4a1-3a90-401b-b946-bfa1fc6ad7a2
}