Hi!
Defining an entity with appengine-magic is straightforward:
----
(ns tlog.models
(:require [appengine-magic.services.datastore :as ds]))
(ds/defentity Article [^:key slug, title, body, created-t, updated-t])
----
But there are several places (other files), where that list sans the
first element would be handy and I would like to avoid copy-pasting
[title, body, created-t, updated-t].
ds/defentity is a macro and won't work if it sees functions at compile
time (I hope this way to put it is acceptable, but tell me if my mental
model is lacking).
amaloy helped me with an almost-solution. The following works:
----
(defmacro def-entity-and-attrs [entity-name key attrs]
`(ds/defentity ~entity-name ~(vec (concat ['^:key key] attrs))))
(def-entity-and-attrs Article slug [title, body, created-t, updated-t])
----
But it was meant to be:
----
(defmacro def-entity-and-attrs [entity-name key attrs-name attrs]
`(do (def ~attrs-name ~attrs)
(ds/defentity ~entity-name ~(vec (concat ['^:key key] attrs)))))
(def-entity-and-attrs Article slug
attrs-name [title, body, created-t, updated-t])
----
Fails with: "Unable to resolve symbol: title in this context"
Or if I quote the vector: "clojure.lang.PersistentVector cannot be cast
to clojure.lang.Symbol"
I guess trying to access attrs-name from elsewhere would have been
"fun", anyway.
I would love to simply
----
(def article-attrs '[title, body, created-t, updated-t])
----
and work with that.
It's not the first time I run into a situation where things beg to be
composited/concatenated, but can't be, at least not easily.
Any ideas?
--
Thorsten Wilms
thorwil's design for free software:
http://thorwil.wordpress.com/
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