List<Params> parameters = new List<Params>();
List<InOut> inouts = new List<InOut>();
List<Sensor> sensors = new List<Sensor>();

void MyMethod(List<T> generic_list)
{
}

void Foo(void *var)
{
}

Foo((uint8_t *)var);
Foo((uint16_t *)var);
Foo((uint32_t *)var);

public UserDataSet(List<?> list)
{
}

public UserDataSet<T>(List<T> list)
{
}

 List<T> generic_list = new List<T>();


private void ButtonLoad_Click(object sender, EventArgs e)
{
    switch (data_type)
    {
         case DATA_TYPE_PARAMS:
             List<Params> generic_list = LoadParametersFromFile(file_path);
             break;

          case DATA_TYPE_INOUT:
              List<InOut> generic_list = LoadInOutsFromFile(file_path);
              break;
     }
}

public List<Params> LoadParametersFromFile(string file)....

public List<InOut> LoadInOutsFromFile(string file)....

 private void ButtonLoad_Click(object sender, EventArgs e)
{
    string file_path;

    OpenFileDialog ofd = new OpenFileDialog
    {
         Filter = "XML Files (.xml)|*.xml"
    };
          
    DialogResult result = ofd.ShowDialog();

    if (result == DialogResult.OK)
    {
        file_path = ofd.FileName;

        switch (data_type)
        {
             case DATA_TYPE_PARAMS:
                 List<Params> generic_list  = LoadParametersFromFile(file_path);
                 break;

             case DATA_TYPE_INOUT:
                 List<InOut> generic_list = LoadInOutsFromFile(file_path);
                 break;
         }
    }
}

<?xml version="1.0" encoding="utf-8"?>

<PARAMETERS>
    <PARAM ID="1"   Name="SCRSIZE"  Value="1024"   Description="Script size" />
    <PARAM ID="2"   Name="SCRCYC"   Value="100"    Description="Script run cycle (ms)" />
	<PARAM ID="3"   Name="CANENA"   Value="0"      Description="CAN bus enabled (0/1)" />
</PARAMETERS> 

public class Params
    {
        public uint Id { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }
        public int Value { get; set; }
        public string StrValue { get; set; }

    }

 List<Params> parameters = new List<Params>();

 public List<Params> LoadParametersFromFile(string file)
        {
            int msg_count = 0;
            uint uint_val;
            int int_val;
            string str;

            if (parameters != null)
                parameters.Clear();

            XmlDocument xmldoc = new XmlDocument();
            try
            {
                xmldoc.PreserveWhitespace = true;
                xmldoc.Load(file);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
                return null;
            }

            //import data from xml file to CanMessage list
            XmlNodeList nodes = xmldoc.DocumentElement.SelectNodes("/PARAMETERS/PARAM");
            foreach (XmlNode node in nodes)
            {
                try
                {
                    Params param = new Params();

                    uint_val = uint.Parse(node.Attributes["ID"].Value, NumberStyles.Integer); //NumberStyles.HexNumber
                    param.Id = uint_val;

                    str = node.Attributes["Name"].Value;
                    if (!string.IsNullOrEmpty(str))
                        param.Name = "";
                    else
                        param.Name = str;

                    if (int.TryParse(node.Attributes["Value"].Value, out int_val))
                    {
                        param.Value = int_val;
                        param.StrValue = int_val.ToString();
                    }
                    else
                    {
                        param.StrValue = "";
                    }

                    //can be empty
                    str = node.Attributes["Description"].Value.ToString();
                    if (!string.IsNullOrEmpty(str))
                        param.Description = str;

                    parameters.Add(param);
                }
                catch
                {
                    continue;
                }
            }

            return parameters;
        }