Generating a Unique Identifier for Each Page Instance

Sometimes there may be a need for identifying each page instance univocally. One ocasion may be, for example, if we want to store something in a session which is specific to a certain page.

What I did was override the Page class' ID property and have it return a unique value for a page that is kept throughout all postbacks. Here is my code:

publicoverride String ID
{
get
{
String id = null;
if ((this.IsPostBack == true) && (String.IsNullOrEmpty(this.Context.Request.Form["__ID"]) == false))
{
id = this.Context.Request.Form["__ID"];
}
elseif (String.IsNullOrEmpty(this.Context.Items [ "__ID" ] as String) == false)
{
id = this.Context.Items [ "__ID" ] as String;
}
else
{
id = Guid.NewGuid().ToString(); this.Context.Items [ "__ID" ] = id;
}
return (id);
}
}
protectedoverridevoid OnPreInit(EventArgs e)
{
this.ClientScript.RegisterHiddenField("__ID", this.ID); base.OnPreInit(e);
}

If you have better solution, just tell me !