Re: Tapestry and Clojure

[Thiago H de Paula Figueiredo]

On Thu, 18 Dec 2014 20:01:11 -0200, Ilya Obshadko  
<ilya.obsha...@gmail.com> wrote:

One more question regarding ObjectLocator.
Turns out it cannot resolve services like Logger, complaining that no
service implements its interface.
Could you suggest how to solve it?

Have you tried getObject() instead of getService()? Logger isn't a  
Tapestry-IoC service (unless you create it, of course), so you cannot use  
getService() to get it.

By the way, as someone who wants to learn Clojure, could you please  
explain your Clojure snippet? :)


On Thu, Dec 18, 2014 at 11:20 PM, Ilya Obshadko <ilya.obsha...@gmail.com>
wrote:

So, my solution for this is actually quite simple:

(ns com.xdance.tapestry.serviceregistry

  (:import (org.apache.tapestry5.ioc ObjectLocator)))


(def ^:dynamic ^ObjectLocator *tapestry-registry-ref* (promise))


(defn init-registry [^ObjectLocator registry]

  "Must be called during service initialization to set up Tapestry
registry object"

  (deliver *tapestry-registry-ref* registry))


(defmacro with-tapestry-services [service-bindings & body]

  "Apply service bindings to body"

  (let [service-binding-pairs (partition-all 2 service-bindings)

        service-binding-exprs (map #(vector (first %1) `(.getService (
deref *tapestry-registry*) ~(second %1))) service-binding-pairs)

        service-binding-final (vec (reduce concat  
service-binding-exprs))]

    `(let ~service-binding-final ~@body)))


The only thing I need to do is to bind init-registry function to  
Tapestry
service interface and call it during startup phase. There might be  
better
approaches probably.

On Thu, Dec 18, 2014 at 6:49 PM, Ilya Obshadko <ilya.obsha...@gmail.com>
wrote:

Thanks Howard, that's making a lot of sense.

However my initial though was about injecting Clojure globals
(specifically, one global containing service registry) during the call  
to
"require" IFn. I still couldn't find any ways to manipulate initial  
Clojure
environment, although there are obvious workarounds (for example I  
could
have a specific function inside Clojure namespace that could be used to
inject necessary objects using mutable globals). I'm still looking for  
more
concise and accurate way to do that.

On Thu, Dec 18, 2014 at 7:35 AM, Howard Lewis Ship <hls...@gmail.com>
wrote:

Actually, Clojure interop with Java is very good, so a Clojure  
function
could be passed a Java object:

(defn frobnicate-the-request
  [^Request request]
  (.setAttribute request "xyzzyx" (compute-the-magic-name)))

The ^Request part is a type hint, it allows the Clojure compiler to
generate proper bytecode to access the methods of the request without
using
reflection.

You quickly get used to the leading dot (which itself is sugar syntax
over
the more primitive interop special form).

Now, in terms of Clojure interop ... the library I put together ago  
on a
whim was about efficiently exposing Clojure functions bundled  
together as
an arbitrary Java interface.

If you pass the Registry to a Clojure function, it will be quite  
capable
of
pulling out whatever it needs.

A lot of the capabilities of Clojure are very familiar to Tapestry  
users:
thread bound values (inside Clojure vars) for example.

My primary thought about integrating Clojure would be to allow a  
Tapestry
app to jump into Clojure to work with the Datomic APIs natively,  
rather
than the Java API to Datomic, which is decidedly second class.

On Tue, Dec 16, 2014 at 5:24 AM, Thiago H de Paula Figueiredo <
thiag...@gmail.com> wrote:
>
> On Mon, 15 Dec 2014 18:29:22 -0200, Ilya Obshadko <
ilya.obsha...@gmail.com>
> wrote:
>
>
>  How are Java objects usually passed to Clojure code? The  
recommended
way?
>>>
>>
>> Java objects are passed to Clojure functions in exactly the same  
way
they
>> are passed to Java method (because internally Clojure function is
just an
>> implementation of IFn interface, and function call is invoke(...)  
on
its
>> instance).
>>
>
> Now I was the one who hasn't made a clear question. :) I'm not  
asking
> about how Clojure passes function arguments. I meant when you call
Clojure
> code from Java code, how do you pass a Java object so it can be used
inside
> Clojure code?
>
>  But I don't want to pass services to Clojure functions, I'd like to
>> inject them into Clojure namespace when clojure.core/require is
executed.
>>
>
> Got it. I have no idea how to do that given my almost no knowledge  
of
> Clojure. But I guess there's some way of doing that.
>
>
> --
> Thiago H. de Paula Figueiredo
> Tapestry, Java and Hibernate consultant and developer
> http://machina.com.br
>
>  
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--
Howard M. Lewis Ship

Creator of Apache Tapestry

The source for Tapestry training, mentoring and support. Contact me to
learn how I can get you up and productive in Tapestry fast!

(971) 678-5210
http://howardlewisship.com
@hlship




--
Ilya Obshadko




--
Ilya Obshadko






--
Thiago H. de Paula Figueiredo
Tapestry, Java and Hibernate consultant and developer
http://machina.com.br

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