2009/10/28 Tiago Antão <tiagoan...@gmail.com>
>
> Hi,
>
> Sorry for the newbie question, but I am trying to understand how to
> construct and call java dynamically from clojure.
> As an example, imagine that there is a bean property called "Bla" and
> one wants to set Bla to 1 on object x, which has that property.
> So, the objective would be to construct, the following java equivalent
>
> x.setBla(1);
>
> I defined a macro called setProperty like this:
> (setProperty "Bla" x 1)
>
> And the definition is (very wrong):
> (defmacro setProperty [field obj value]
> `(let [cct# (symbol (.concat ".set" ~field))]
> (cct# ~obj ~value)
> )
> )
If "field" is only ever going to be a literal:
(defmacro setProperty [field obj value]
(let [cct (symbol (.concat ".sub" field))]
`(~cct ~obj ~value)))
user=> (setProperty "string" "foobar" 3)
"bar"
Of course in that case it's nicer if you can omit the quotation marks:
(defmacro setProperty [field obj value]
(let [cct (symbol (.concat ".set" (str field)))]
`(~cct ~obj ~value)))
user=> (macroexpand-1 '(setProperty Bla x 1))
(.setBla x 1)
But this won't work if the first argument to setProperty is an expression
that evaluates to Bla rather than the literal symbol Bla.
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