I'm trying to figure out the best way to use clojure.core/memoize
while retaining the original function's docstrings, tags, etc. for the
memoized function. The best way I've seen to do this is James Reeves'
decorate-with function from Compojure, which applies a "decorator" --
Python's name for a higher-order function, like memoize, that takes a
function f & returns f' that's a version of f modified in some useful
way -- to already-defined functions, like
(defn costly-fn [x]
(costly-computation x))
(decorate-with memoize costly-fn)
The most useful thing about decorate-with is its side-effecting code
that redefines the root binding of the costly-fn var while keeping its
original metadata. This is done by the redef function, which is (with
a few minor differences from the Compojure version):
(defmacro redef
"Redefine an existing value, keeping the metadata intact."
[name value]
`(let [m# (meta (var ~name))
v# (def ~name ~value)]
(alter-meta! v# merge m#)
v#))
Question: is there a better way of using decorators than this? If not,
is there any interest in including redef & decorate-with (see below)
in contrib, either, perhaps, in c.c.def or c.c.macros?
Thanks,
Perry
(defmacro decorate-with
"Wrap functions in a decorator."
[decorator & funcs]
`(do ~@(for [f funcs]
`(redef ~f (~decorator ~f)))))
Compojure's compojure.control library: http://bit.ly/17U7m
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