I think that's what is going on too. I tried quoting catch in the rethrow
macro, but that didn't do it (didn't expect it to either).
(defmacro rethrow [ex-class] `('catch ~ex-class x# (throw x#)))
I still wonder if there is some sort of macrofoolery that would get it past
the compiler. I'm not going to hold my breath though.
-Bill
On Monday, April 1, 2013 1:26:43 PM UTC-4, Alf wrote:
>
> Hey Bill.
>
> I am guessing the problem is that the rethrow macro is expanded and passed
> to the reader/compiler before the handle-ex macro is. And at that point the
> compiler sees catch as a "standalone-symbol", not as part of the try
> special form. Macro-experts, please correct me :)
>
> Tried to quickly catch up with
> http://www.infoq.com/presentations/Clojure-Macros, but infoq seems slow.
>
> Cheers,
> Alf
>
>
> On 1 April 2013 17:21, Bill Robertson <billrob...@gmail.com
> <javascript:>>wrote:
>
>> I was all excited when I was able to consolidate a lot of try/catch logic
>> behind a macro earlier this morning. All was good.
>>
>> I felt like I could do a better job of communicating my intentions in the
>> code though with a rethrow construct rather than writing
>> (catch FooException #f (throw #f))
>>
>> I would have liked to have been able to simply write
>> (rethrow FooException)
>>
>> This failed. Poking around the docs a bit, I see that try/catch is a
>> special form. Which makes sense.
>>
>> user=> (defmacro rethrow [ex-class] `(catch ~ex-class x# (throw x#)))
>> #'user/rethrow
>> user=> (defmacro handle-ex [message & body] `(try ~@body (rethrow
>> IllegalArgumentException) (catch Exception x# (throw
>> (IllegalArgumentException. message)))))
>> #'user/handle-ex
>> user=> (handle-ex "no" (throw (IllegalArgumentException. "yes")))
>> CompilerException java.lang.RuntimeException: Unable to resolve symbol:
>> catch in this context, compiling:(NO_SOURCE_PATH:1:1)
>>
>> It was a longshot, but I tried to qualify catch. That fails too, because
>> it's not really there...
>>
>> user=> (defmacro rethrow [ex-class] `(clojure.core/catch ~ex-class x#
>> (throw x#)))
>> #'user/rethrow
>> user=> (defmacro handle-ex [message & body] `(try ~@body (rethrow
>> IllegalArgumentException) (catch Exception x# (throw
>> (IllegalArgumentException. message)))))
>> #'user/handle-ex
>> user=> (handle-ex "no" (throw (IllegalArgumentException. "yes")))
>> CompilerException java.lang.RuntimeException: No such var:
>> clojure.core/catch, compiling:(NO_SOURCE_PATH:1:1)
>>
>> Is this possible to do within the normal bounds of the language?
>>
>> Thanks!
>>
>>
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