How to generate clojure code to call java method at run time?

Question

I want to use Java reflection method with in Clojure function. I think the code like (.toString {:a 1}) will parse and compile by clojure reader. So, it works by use clojure macro. But if I want to define a function to call java object method at run time , it failed. I have no idea how to invoke this kind of code with in clojure.

Here is my demo code:

 (def jmethod ".toString")
 (defn call-java-method [mname & body]
     (let [fn1 (fn [] `(~(symbol mname) ~@body))]
        (fn1)))

 user=> (call-java-method jmethod 3.4M)

The result is a list (.toString 3.4M) , but I want to eval this list as a clojure function call.

Valentin Waeselynck Valentin Waeselynck · Accepted Answer · 2016-10-23T07:23:05

As you have realized, since macros 'operate at compile-time', you essentially can't use them to call a dynamically-resolved method.

You have 2 options:

use the Java Reflection API
use clojure.core/eval, which consists using Clojure as a runtime compiler to compile your code, then execute it.

How to generate clojure code to call java method at run time?

1 Answers