On DZone.com Giorgio Sironi has posted a refactoring recommendation around the handling of the data and types in your PHP code. He suggests the move from just a simple variable to a Value Object (noting that it's not really needed in PHP, but can provide a "richer interface" to work with the data).
Statically typed languages sometimes encounter the problem of downcasting: the compiler is only able to guarantee a basic type, and the object contained instead is an instance of a richer subtype. [...] You'll never need to downcast objects: variables can contain handlers to objects or even scalars without compile-time checks. Casting with (ClassName) is not even supported by the language (while casting a non-object with (object) will give you a stdClass.)
He starts by talking about scalar values in PHP and a simple form of downcasting - using the casting notation included in the language. From there he moves into the conversion into Value Objects and some of the updates (like docblocks) that would come with their use. He outlines some steps towards the conversion and provides an example set of scripts showing the conversion process.