Hello
I've recently found out just what a good invention agents are. I find
them to handle a few idioms I see in other languages very nicely. I
started changing some of my code over to it, and it has really helped
the structure. But I was a little surprised to find out that by
default, if you don't return anything, it will set the value of the
agent to nil. I see two problems with this: it's makes the code
verbose and it leads to subtle bugs. So I cooked up a little macro (be
gentle, it's my first real macro :)) to on nil, just return the state
instead.
(defmacro defa [name args & form]
`(defn ~name [...@args]
(let [result# (do ~...@form)]
(cond (not result#)
(first ~args)
:else
result#))))
Hopefully somebody will find it useful, I was contemplating if it
should also add state as the first parameter to the function, sort of
like this in OO languages, but I decided not to. It's a bit intrusive
and also my macro knowledge didn't allow me to write it ;-)
--
Anders Rune Jensen
http://people.iola.dk/arj/
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