I've got a few namespaces that use similar functions, but with slight
variations. I was thinking of using a macro to generate the
repetitive bits of this code, but I'm just not able to get past Cons
exceptions and missing symbols.
Here's a simple version of what I'm trying to do. Right now, I have a
bunch of namespaces that have something like this at the top:
(def ^:const TYPE "user")
(defn index [& [property value]] (db/get-index TYPE property
value))
(defn find-user [property value] (index property value))
(defn by-login [value] (find-user :login value))
(defn by-email [value] (find-user :email value))
What I'd like to do is something like this:
(defmacro defnode
[type-name & settings]
`(do (def (symbol "TYPE") (str ~type-name))
(defn (symbol "index") [] (db/get-index (symbol "TYPE")))
(defn (symbol (str "find-" ~type-name)) [property# value#]
((symbol "index") property# value#))
(doseq [property# (apply hash-map settings)]
(defn (symbol (str "by-" (name property#))) [value#]
((symbol (str "find-" ~type-name)) value#)))))
(Obviously this code is wrong--it's sort of Clojure pseudo-code--but
hopefully you get the gist).
So that all that code previously becomes:
(defnode user
:index-by [:login :email])
And when the app is compiled, I should be able to do something like:
user=> user/TYPE
"user"
user=> (user/index)
#<SearchIndex LuceneIndex$SearchIndex@7e270dad>
user=> (user/by-login "Bob")
{:name "Bob" :password "xyz" :created "Oct. 10, 2011"}
I've tried using intern rather than the macro templates, but I'm not
sure that's working either. My biggest problem is dereferencing the
symbols I've created previously. For example, if I create the var for
TYPE in the namespace, how do I reference that in my functions? Or
once I create the "find-?" function, how do I call that from the
subsequent (by-*) functions?
Or am I just asking too much from the macros?
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