On Fri, Jun 17, 2011 at 11:51 PM, Jian Liu <liuj...@gmail.com> wrote:
> Hi Clojure Gurus :)
>
> I've a somewhat contrived use-case for macros that I've been
> struggling with.
>
> Let's say there's an interface called EWrapper that I'm trying to
> implement with methods "tickPrice" and "tickSize", a concrete class
> EWrapperMsgGenerator that has methods with those names that return
> strings.
>
> I'd like to write a macro that proxies EWrapper's tickSize and
> tickPrice methods so that they print out the method name as well as
> the string returned from EWrapperMsgGenerator.
>
> E.g. (in java code):
> public tickSize( args ) { // on the proxied EWrapper
> System.out.println( "tickSize: " +
> EWrapperMsgGenerator.tickSize( args ) )
> }
>
> Here's what I've come up with so far:
>
> (defmacro make-msg-ewrapper [method-names]
> `(proxy [EWrapper] []
> ~@(map
> (fn [method-name]
> `(~(symbol method-name) [& args#]
> (println ~method-name ":"
> (. EWrapperMsgGenerator ~(symbol method-name)
> args#))))
> method-names)))
>
> It's a bit messy -- I'm splicing in a map evaluation into proxy, and
> then writing in symbols in the function body. This works except that
> when I run the macro I get "No matching method: tickSize" referring to
> EWrapperMsgGenerator.
>
> The macro expansion looks like:
>
> (let* [p__4736__auto__ (new user.proxy$java.lang.Object$EWrapper
> $11bc5609)] (clojure.core/init-proxy p__4736__auto__ {tickPrice
> (clojure.core/fn ([this & args__2058__auto__] (clojure.core/println
> tickPrice : (. com.ib.client.EWrapperMsgGenerator tickPrice
> args__2058__auto__)))), list (clojure.core/fn ([this &
> args__2058__auto__] (clojure.core/println list : (.
> com.ib.client.EWrapperMsgGenerator list args__2058__auto__))))})
> p__4736__auto__)
>
> So far this looks fine to me, except that tickPrice within the
> EWrapperMsgGenerator call isn't scoped. Is there a better way to do
> this?
>
> Thanks,
> Jian
>
Do you have a working version of the code you want that doesn't involve a
macro?
David
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