Avoid capturing serialize value in clj-item->db-item

[gusbicalho]

The goal of the ISerializable protocol is to allow extending the serialization mechanism to custom types, via extend-protocol. For example, we can (extend-protocol ISerializable UUID (serialize [id] ...)) to implement serialization for UUIDs.

This extend-protocol call works by redefining the serialize function, i.e. creating a new function and changing the #'serialize var to point to this new object. The new function knows how to dispatch to the correct implementation for the types specified in the extend-protocol.

However, the implementation of clj-item->db-item using partial captures the value of the serialize function at the moment the namespace is loaded. Therefore, it will ignore any further extend-protocol calls - these will replaced the value referenced by the #'serialize var, but the clj-item->db-item function will still hold a reference to the original serialize function object.

To solve this, we have to ensure we always go through the #'serialize var when we run clj-item->db-item. This can be done in one of two ways:

• Make partial capture the #'serialize var, instead of the value of that var:

  (partial utils/name-map #'serialize)

• Avoid partial altogether and just use normal function call syntax to call serialize. This will look up the serialize symbol in the faraday namespace, which will point to the #'serialize var, which in turn will point to the update serialize function object`

  (defn clj-item->db-item [item]
  (utils/name-map serialize item))

I choose the latter solution because it seemed easier to understand.