seems similar to this concept with "new":
=>* (new java.lang.RuntimeException "msg")* ;works this way
#<RuntimeException java.lang.RuntimeException: msg>
=> *(def a java.lang.RuntimeException)*
#'runtime.q/a
=> *a*
java.lang.RuntimeException
=> *(new a "msg")* ;nope
CompilerException java.lang.IllegalArgumentException: Unable to resolve
classname: a, compiling:(NO_SOURCE_PATH:1:1)
=> *(new (eval a) "msg")* ; nope
CompilerException java.lang.IllegalArgumentException: Unable to resolve
classname: (eval a), compiling:(NO_SOURCE_PATH:1:2)
=> *(defmacro new-instance [cls & args]*
* `(new ~(eval cls) ~@args))*
#'runtime.q/new-instance
=> *(new-instance a "msg")* ; works
#<RuntimeException java.lang.RuntimeException: msg>
=> *(new-instance 'java.lang.RuntimeException "msg")* ;also works
#<RuntimeException java.lang.RuntimeException: msg>
or with "."
=> *(defmacro call-method [inst m & args]
`(. ~inst ~(symbol (eval m)) ~@args))*
#'runtime.q/call-method
=> *(def someInst "somestringinstance")*
#'runtime.q/someInst
=> *(call-method someInst 'toUpperCase)*
"SOMESTRINGINSTANCE"
=> *(call-method someInst "toUpperCase")*
"SOMESTRINGINSTANCE"
=> *(call-method someInst toUpperCase)*
CompilerException java.lang.RuntimeException: Unable to resolve symbol:
toUpperCase in this context, compiling:(NO_SOURCE_PATH:1:1)
=> *(def four (* 2 2))*
#'runtime.q/four
=> *(call-method someInst 'substring (+ 1 1) four)*
"me"
=> *(call-method someInst "substring" (+ 1 1) four)*
"me"
=> *(call-method "abcde" (quote substring) 2 four)*
"cd"
On Tue, Feb 12, 2013 at 1:53 AM, juan.facorro <[email protected]>wrote:
> Since a macro's arguments must be available at compile time, creating one
> for calling a runtime defined method won't work.
>
> Because of this we are left with *eval*, which actually compiles and then
> evaluates at runtime the expression it receives as an argument.
>
> Here's a function that receives an object, a method name (as a symbol or
> string) and optional arguments; and then uses eval to find the result:
>
>
> (ns calling-methods
> (:require [clojure.reflect :as r]))
> ;-----------------------------
> (defn call-method* [obj m & args]
> (eval `(. ~obj ~(symbol m) ~@args)))
> ;-----------------------------
> (def method-def (->> (r/reflect "String")
> :members
> (filter #(= "toString" (str (:name %))))
> first))
>
> (let [x {:a 1 :b 2}
> s "hi"
> upper "toUpperCase"]
> (println (call-method* x (:name method-def)))
> (println (call-method* "hi" (:name method-def)))
> (println (call-method* "hi" upper)))
>
>
> Hope it helps.
>
> J
>
>
> On Monday, February 11, 2013 5:34:00 PM UTC-3, Bauna wrote:
>>
>> Hey all,
>> I'm a newbie that is trying to use clojure for my university grade
>> thesis.
>> In our project we have to generate a graph structure invoking some
>> methods on a standard java class. This class is provided at run time, so
>> the methods that need to be called must be obtained by
>> reflection. I've been trying to use clojure.reflect, but I was not able
>> to find a way to invoke a method on the class with the symbols retrieved
>> from reflect (I know that I can use java interop and
>> use standard java reflection api).
>>
>> Here is and example of what I want to do:
>> user=> (require '[clojure.reflect :as r])
>> user=> (def method-def (filter #(= "toString" (str (:name %))) (:members
>> (r/reflect "aClass"))))
>>
>> How do I invoke "toString" using "method-definition"?
>>
>> Thanks and regards,
>> --
>> Pablo Nussembaum
>>
>>
>>
>> what is better to use java interop using java reflection API or use
>> clojure.reflect to option
>>
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--
Please correct me if I'm wrong or incomplete,
even if you think I'll subconsciously hate it.
--
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