C# - Downside to Setting Initial Value in Declaration

Question

Is there any downside to a class like:

class Example1
{
  protected string UserId = (string)Session["user"];
}
//versus

class Example2
{
  protected string UserId;
  public Example2()
  {
      UserId = (string)Session["user"];
  }
}

If I always want to set this value is there any downside to Example1?

UPDATE:
Session["user"] is set in the Global.asax Session_Start. So if this fails. Nothing should work anyways.

Answer 1

Your biggest problem is if this protected string UserId = (string)Session["user"]; fails. You have no recourse to degrade gracefully. By putting it in the constructor etc. You can check the Session and make a decision on what to do.

As a general rule, I only try and put values that I know are going to succeed like UserId = -1; etc. and then modify them in a code block when I need to. You never know when something is going to go wrong and you need to recover from it.