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Nathan Marz built a great Proxy library called proxy-plus. This project is first and foremost a copy of that work. I'm aiming to make a few significant changes:

  1. Lint & push code towards my preferred style. This is where the minus in the name is a factor.
  2. Despecialise the dependencies: generic ASM libraries so that the documentation is easier to look up (although RPL's Rama project does sound interesting).
  3. Support a (proxy-super+ ...) function/macro. Vanilla Clojure has a crippling bug in proxy-super and there is an opportunity here to work around it.

proxy+- is a replacement for Clojure's proxy that's faster and more usable. proxy has a strange implementation where it overrides every possible method and uses a mutable field to store a map of string -> function for dispatching the methods. This causes it to be unable to handle methods with the same name but different arities.

proxy+- fixes these issues with proxy. Usage is like reify, and it's up to 10x faster.


This library provides the macro proxy+-. The first argument is fields to provide to the superclass's constructor. Next comes reify-like definitions to provide overrides. When extending a base class, the base class should come first. Example usage:

(ns example
  (:require [cc.riddy.proxy-plus-minus :refer [proxy+- proxy-super+-]]))

(proxy+- [super-arg1 super-arg2]
  (foo [this] -1)
  (foo [this a b] (+ a b))

  (bar [this a b c] (* a b c))

  (bar [this] 100))

;; TestBaseClass3 has a .getInt method that returns 100
(let [o
      (proxy+- []
        (getInt [this] (.intValue 3)))]
  (is (= 100 (proxy-super+- getInt o))))


Isn't proxy+- a terrible name?

~ Me

Yes. This project contains several hacks and we all wish that clojure.core would fix up the proxy-super macro so that this wasn't necessary, or think of a way for to provide compiler support for the proxy-plus project. I've had trivial documentation PRs sit waiting for months to get in to Clojure website and I'd like a working proxy-super in September so this hack is the next best thing. But the name is a passive reminder that if any alternative library suits your use case then that is the preferred option.


Copyright 2020 Red Planet Labs, Inc. proxy-plus-minus is licensed under Apache License v2.0.

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