place script.clj in ~/.ccw

gistfile1.clj

(ns lein-script-test
  (:require [ccw.util.eclipse :as e]))

(defn greet [context] 
  (e/info-dialog "Hello world"
                 "This popup provided to you from a user script"))

(defn handler-factory [context] (ccw.util.GenericHandler. #'greet))

;; last form of the script is an application model fragment to be merged into the Application Model
{:fragment-id "lein-script-test"
 :commands [{:element-id  "lein-script-test/commands/greeter"
             :command-name "Greetings from CCW"
             :category     "org.eclipse.ui.category.window"}]
 :handlers [{:command      "lein-script-test/commands/greeter"
             :contribution-URI "bundleclass://ccw.core/clojure/lein-script-test/handler-factory"}]}}

gistfile2.clj

(ns lein-script-test
  (:require [ccw.util.eclipse :as e]))

(defn greet [context] 
  (e/info-dialog "Hello world"
                 "This popup provided to you from a user script"))

(defn handler-factory [context] (ccw.util.GenericHandler. #'greet))

(defn run []
  {:fragment-id "lein-script-test"
   :commands [{:element-id  "lein-script-test/commands/greeter"
              :command-name "Greetings from CCW"
               :category     "org.eclipse.ui.category.window"}]
   :handlers [{:command      "lein-script-test/commands/greeter"
               :contribution-URI "bundleclass://ccw.core/clojure/lein-script-test/handler-factory"}]}}

lein-script-test.clj

(require '[ccw.util.eclipse :as e])

(defn greet [context] 
  (e/info-dialog "Hello world"
                 "This popup provided to you from a user script"))

{:commands [{:command-name "Greetings from CCW"
             :handler      #'greet}]}
 
; fragment-id is derived from script path: will be stable for a given installation
; commands with a single general handler have simplified :handler key
; :handler key instead of contributor-URI which will be automatically created "bundleclass://ccw.core/clojure/lein-script-test/handler-factory"
; command element-id can be omitted in which case it will be a random GUID
; :category will be "org.eclipse.ui.category.window" by default

script.clj

(ns lein-script-test
  (:require [ccw.util.eclipse :as e]
            [ccw.util.e4.model :as m]))

(defn greet [context] 
  (e/info-dialog "Hello world"
                 "This popup provided to you from a user script"))

(defn handler-factory [context] (ccw.util.GenericHandler. #'greet))

(let [app @m/app
      cmd-id "c9"
      command (m/make-command  
                app
                {:element-id   "lein-script-test/commands/greeter"
                 :command-name "Greetings from CCW"
                 :category     "org.eclipse.ui.category.window"})
      handler (m/make-handler 
                app
                {:command command
                 :contribution-URI "bundleclass://ccw.core/clojure/lein-script-test/handler-factory"})]
  (-> app (m/add-command! command) (m/add-handler! handler)))