Run-time assembly creation

There are times where you may need to generate Assembly dynamically at run-time.  The blog post shares some code for the same.

public CompilerResults Compile()
{
    //Set the compiler options
    var compilerOptions = new Dictionary<string, string>();
    compilerOptions.Add("CompilerVersion", "v4.0");

    CodeDomProvider compiler = new CSharpCodeProvider(compilerOptions);
    CompilerParameters parameters = new CompilerParameters();
    parameters.WarningLevel = 4;
    parameters.TreatWarningsAsErrors = false;
    parameters.GenerateExecutable = false;
    parameters.GenerateInMemory = false;
    parameters.OutputAssembly = GetFileName();
    parameters.IncludeDebugInformation = false;
    if (RoleEnvironment.IsAvailable)
        parameters.TempFiles = new TempFileCollection(RoleEnvironment.GetLocalResource("CompilerTempFiles").RootPath, false);

    string baseDir = Path.GetDirectoryName(
                           Assembly.GetExecutingAssembly().Location);
    baseDir = baseDir.Substring(0, 
                       baseDir.LastIndexOf(Path.DirectorySeparatorChar));
    baseDir = baseDir.Substring(0, 
                       baseDir.LastIndexOf(Path.DirectorySeparatorChar));

    //Add required assembly references of your code
    string assemblyName;
    foreach (string assembly in GetReferences())
    {
        string suffix = assembly.EndsWith(".exe") ? "" : ".dll";

        assemblyName = assembly;
        if (!assembly.StartsWith("System"))
        {
            if (assembly.IndexOf(".dll") > -1)
            {
                assemblyName = FindAssembly(baseDir, assembly);
                suffix = "";
            }
            parameters.ReferencedAssemblies.Add(assemblyName + suffix);
        }
        else
        {
            var assemblyPath = (from assm 
                  in AppDomain.CurrentDomain.GetAssemblies()
                  where assm.FullName.IndexOf(assemblyName + ",") > -1
                                select assm).FirstOrDefault();

            if (assemblyPath == null)
            {
                throw new Exception("Unable to locate assembly: " 
                                      + assemblyName + suffix);
            }

            parameters.ReferencedAssemblies.Add(assemblyPath.Location);
        }
    }

    //Get your dynamic code
    string Code = GetCodeText();
            
    CompilerResults results = compiler.CompileAssemblyFromSource(
                                               parameters, Code);

    return results;
}

With dynamic code you must have some known interface, so that you can create the dynamic object of given interface to invoke the code.

public IKnownInterface GetTableServiceContext()
{
    string assemblyPath = GetFileName();
    if (!File.Exists(assemblyPath))
    {
        throw new FileNotFoundException(assemblyPath + " not found");
    }

    System.Reflection.Assembly assem = AppDomain.CurrentDomain.Load(
        File.ReadAllBytes(assemblyPath));

    Type queryType = assem.GetType("DynamicClassName");

    return Activator.CreateInstance(queryType) as IKnownInterface;        
}

We should be avoiding dynamic code generation and look for solutions like dependency injection, MEF frameworks.