thanks for the lengthy reply! i will play around with these
suggestions. like the fact there are less parameters to pass around.
On Tue, Sep 28, 2010 at 1:10 AM, Meikel Brandmeyer <m...@kotka.de> wrote:
> Hi,
>
> I'm not sure my solution is 100% idiomatic, but has some advantages.
> General strategy: minimise macro usage. Macros are cool, but
> overrated. Put as much as possible into functions. This has several
> advantages like easier testing, less macro trap doors, better
> readability (no # all over the place) or possibility of hotfixing of
> eg. the cleanup code in with-context[1], etc.
>
> So my plan is: put everything in special global variables. Expose them
> as options for the functions. The defaults refer to the global
> variables which are set with binding. So allows for usage pattern, but
> could also allow for easy testing.
>
> (with-context [:some option]
> (init-source "bla" :some "option"))
>
> or
>
> (init-source "bla" :some "option" :context manually-crafted-context)
>
> Here is my try:
>
> (declare *context* *thread* *receivers* *sources*)
>
> (defn init-receiver
> [topic & {:keys [context receivers]
> :or {context *content* receivers *receivers*}
> :as options}]
> ...boring java stuff)
>
> (defn init-source
> [topic & {:keys [context sources]
> :or {context *content* sources *sources*}
> :as options}]
> ...boring java stuff)
>
> (defn publish
> [topic message & {:keys [context sources]
> :or {context *content* sources *sources*}
> :as options}]
> ...boring java stuff)
>
> (defn receive
> [topic func & {:keys [context receivers]
> :or {context *content* receivers *receivers*}
> :as options}]
> ...boring java stuff)
>
> (defn with-context*
> [options thunk]
> (let [context (create-context options)
> thread (create-thread context)
> sources (atom {})
> receivers (atom {})]
> (binding [*context* context
> *thread* thread
> *sources* sources
> *receivers* receivers]
> (try
> (thunk)
> (finally
> ... close stuff, cleanup)))))
>
> (defmacro with-context
> [options & body]
> `(with-context* ~options (fn [] ~...@body)))
>
> Icying (not tested though, but some quick macroexpands seem to be
> promising):
>
> (defmacro defsugaredfn
> [fnname & fntail]
> (let [[docstring fntail] (let [[docstring & tail :as fntail] fntail]
> (if (string? docstring)
> [docstring tail]
> [nil fntail]))
> [metamap fntail] (let [[metamap & tail :as fntail] fntail]
> (if (map? metamap)
> [metamap tail]
> [nil fntail]))
> args (first fntail)
> fntail (next fntail)
> options (peek args)
> options (when (map? options) options)
> mod-options (merge-with into
> `{:keys [~'context
> ~'receivers
> ~'sources]
> :or {~'context *context*
> ~'receivers
> *receivers*
> ~'sources *sources*}
> :as ~'options}
> options)
> args (if options
> (pop args)
> (conj args '&))
> args (conj args mod-options)]
> `(defn ~fnname
> ~@(concat (when docstring [docstring])
> (when metamap [metamap])
> [args])
> ~...@fntail)))
>
> Use as:
>
> (defsugaredfn init-receiver
> "with docstring! yeah!"
> [topic & {:keys [some] :or {some "option"}}]
> ...boring java stuff)
>
> or
>
> (defsugaredfn init-receiver
> [topic]
> ...boring java stuff)
>
> context, receivers, source and options will be captured this way and
> available in the "boring java stuff" part. Another downside: you have
> to take care when you cross thread boundaries. Then you have to use
> bound-fn or pass the context and friend explicitely.
>
> (with-context [:some "option"]
> ...
> (bound-fn [] (init-receiver "in another thread"))
> ...
> (fn [] (init-receiver "in another thread" :context
> context :receivers receivers)
> ,...
> )
>
> Hope that helps.
>
> Sincerely
> Meikel
>
> [1]: With a macro the client code has to be recompiled.
>
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