Example of a CodeDom (predates Roslyn) based meta program

CodeDom.cs

public static Assembly Compile(string[] sources, bool isDebug, string tempDir, params AssemblyName[] referencedAssemblies)
{
    var codeProvider = new CSharpCodeProvider(new Dictionary<string, string> {{"CompilerVersion", "v4.0"}});
 
    var assemblyReferences = new[]
        {
            "System.dll",
            "System.Core.dll",
            "mscorlib.dll"
        }
        .Union(from ass in referencedAssemblies
                select new Uri(ass.CodeBase).LocalPath)
        .Distinct(StringComparer.OrdinalIgnoreCase)
        .ToArray();
 
    var parameters = new CompilerParameters
        {
            GenerateInMemory = true,
            GenerateExecutable = true,
            IncludeDebugInformation = isDebug,
            OutputAssembly = Path.Combine(tempDir, "generatedassembly.dll")
        };
 
    parameters.ReferencedAssemblies.AddRange(assemblyReferences);
 
    if (tempDir.Length > 0) parameters.TempFiles = new TempFileCollection(tempDir);
    parameters.TempFiles.KeepFiles = isDebug;
 
    var compilerResults = codeProvider.CompileAssemblyFromSource(parameters, sources);
 
    if (compilerResults.Errors.HasErrors)
    {
        var message = string.Join("\r\n", compilerResults.Errors);
        throw new ApplicationException(message);
    }
 
    return compilerResults.CompiledAssembly;
}