A typesafe container for data with a lifetime nominally equivalent to the lifetime of a page rendered by an HTTP request. RequestVars maintain their value throughout the duration of the current HTTP request and any callbacks for servicing AJAX calls associated with the rendered page. RequestVar instances have no value at the beginning of request servicing (excluding AJAX callbacks) and their value is discarded at the end of request processing. They are commonly used to share values across many snippets. Basic usage: object MySnippetCompanion { object myRequestVar extends RequestVar[String]("hello") } The standard pattern is to create a singleton object extending RequestVar instead of creating an instance variable of a concrete RequestVar subclass. This is preferred because RequestVar will use the name of its instantiating class for part of its state maintenance mechanism. If you find it necessary to create a RequestVar subclass of which there may be more than one instance, it is necessary to override the __nameSalt() method to return a unique salt value for each instance to prevent name collisions.

param

dflt - - the default value to be returned if none was set prior to requesting a value to be returned from the container