On Mon, Aug 3, 2009 at 8:01 PM, CuppoJava <patrickli_2...@hotmail.com>wrote:
>
> You can use eval to retrieve the value of a-map when the macro is
> expanded.
>
> (let [value (eval a-map)]
> `(binding ~(vec (process-a-map value)) ~...@forms))
>
> I've programmed some substantial programs now in Clojure though, and
> I've never had to use this. Perhaps there is another way to achieve
> what you want?
>
> As a rule of thumb that I use, using a macro should only look like a
> syntax extension. There shouldn't be any dependance on the values of
> any of the arguments.
Eh, I hadn't noticed that; he's using process-a-map already in a ~
expression. That's the sort of thing more usually done in a helper function:
(defn binding-from-map [a-map forms]
`(binding ~(vec (process-a-map a-map)) ~...@forms)))
Then call from a macro:
(defmacro foo [map & body]
(binding-from-map map body))
(foo {:a 1} (fn1 arg1) (fn2 arg2 arg3))
If you really want to call the eventual macro with a non-literal map,
though, then you'll need it to eval that argument as Patrick says.
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