System.CodeDom.Compiler.TempFileCollection.AddFile C# (CSharp) Method

        public void AddFile(string fileName, bool keepFile)
        {
            if (string.IsNullOrEmpty(fileName))
            {
                throw new ArgumentException(SR.Format(SR.InvalidNullEmptyArgument, nameof(fileName)), nameof(fileName));
            }

            if (_files[fileName] != null)
            {
                throw new ArgumentException(SR.Format(SR.DuplicateFileName, fileName), nameof(fileName));
            }

            _files.Add(fileName, keepFile);
        }

		string CompileAndGetOutput(string fileContent)
		{
			TempFileCollection  tf = new TempFileCollection ();
			
			string path = Path.Combine(tf.BasePath, tf.TempDir);
			Directory.CreateDirectory(path);
			string generatedScript = Path.Combine(path, "InternalGeneratedScript.cs");
			string generatedDLL    = Path.Combine(path, "A.DLL");
			tf.AddFile(generatedScript, false);
			tf.AddFile(generatedDLL, false);
			
			StreamWriter sw = new StreamWriter(generatedScript);
			sw.Write(fileContent);
			sw.Close();
			
			string output = String.Empty;
			string error  = String.Empty;
			
			Executor.ExecWaitWithCapture(GetCompilerName() + " /target:library \"/out:" + generatedDLL + "\" \"" + generatedScript +"\"", tf, ref output, ref error);
			
			if (!File.Exists(generatedDLL)) {
				
				StreamReader sr = File.OpenText(output);
				string errorMessage = sr.ReadToEnd();
				sr.Close();
				MessageService.ShowMessage(errorMessage);
				return ">>>>ERROR IN CODE GENERATION GENERATED SCRIPT WAS:\n" + fileContent + "\n>>>>END";
			}
			
			Assembly asm = Assembly.Load(GetBytes(generatedDLL));
			
			object templateInstance = asm.CreateInstance("Template");
			
			
			foreach (TemplateProperty property in item.Properties) {
				FieldInfo fieldInfo = templateInstance.GetType().GetField(property.Name);
				fieldInfo.SetValue(templateInstance, Convert.ChangeType(StringParser.Properties["Properties." + property.Name], property.Type.StartsWith("Types:") ? typeof(string): Type.GetType(property.Type)));
			}
			MethodInfo methodInfo = templateInstance.GetType().GetMethod("GenerateOutput");
			string ret = methodInfo.Invoke(templateInstance, null).ToString();
			tf.Delete();
			return ret;
		}