[SharePoint 2010 - Developpement] Add current user to person field default value with event receiver ItemAdding–SharePoint 2010

I wanted to set a person field default value with my current user, but that doesnt exist in sharepoint.
What i did is :

• I created an event receiver
• I checked if it was my library
• Then i set the person value thanks to the ItemAdding event firing

   1: /// <summary>

   2:        /// An item is being added.

   3:        /// </summary>

   4:        public override void ItemAdding(SPItemEventProperties properties)

   5:        {

   6:            SPSecurity.RunWithElevatedPrivileges(delegate()

   7:            {

   8:                try

   9:                {

  10:                    this.EventFiringEnabled = false;

  11:                    base.ItemAdded(properties);

  12:                    if (properties.List.RootFolder.Name == "libraryInternalName")

  13:                    {

  14:                        SPWeb web = properties.List.ParentWeb;

  15:                        SPList List = properties.List;

  16:                        //replace the id by your person colomn

  17:                        SPField fld = List.Fields[new Guid("03457d42-31a3-4088-b9af-4e3f2e368545")];

  18:                        SPUser usr = web.CurrentUser;

  19:                        SPFieldUserValue defValue = new SPFieldUserValue();

  20:                        defValue.LookupId = usr.ID;

  21:                        fld.DefaultValue = defValue.ToString();

  22:                        fld.Update();

  23:                        List.Update();

  24:                    }

  25:  

  26:                }

  27:                catch (Exception)

  28:                {

  29:                }

  30:                finally

  31:                {

  32:                    this.EventFiringEnabled = true;

  33:                }

  34:            });

  35:        }