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component.repl

Utilities for interactive development using the Component framework and tools.namespace.

This is an extension of the development workflow first described in Workflow Reloaded and codified in the reloaded template.

Releases and Dependency Information

Leiningen dependency information:

[com.stuartsierra/component.repl "0.2.0"]

Maven dependency information:

<dependency>
  <groupId>com.stuartsierra</groupId>
  <artifactId>component.repl</artifactId>
  <version>0.2.0</version>
</dependency>

Usage

Require com.stuartsierra.component.repl in your development namespace.

(ns dev
  (:require
   [com.stuartsierra.component :as component]
   [com.stuartsierra.component.repl
     :refer [reset set-init start stop system]]))

Provide an initializer function to com.stuartsierra.component.repl/set-init to construct a Component system map. The initializer function takes one argument, the old system, usually ignored.

(defn new-system [_]
  (component/system-map
    :server (web-server)
    :database (database)
    :cache (cache)))

(set-init new-system)

At the REPL, use the com.stuartsierra.component.repl/reset function to reload modified source files and restart your system.

example=> (reset)
:reloading (example)
:ok

The current system under development is available as the Var com.stuartsierra.component.repl/system.

example=> (keys system)
(:server :database :cache)

Bootstrapping the user namespace

Clojure will automatically load a file named named user.clj on REPL start-up. Usually it is not a good idea to do to much in user.clj, because any exception thrown while loading user.clj will prevent the REPL from starting.

The namespace com.stuartsierra.component.user-helpers provides a few convenience functions that you can :refer into the user namespace to quickly "boot" the component.repl system.

The user-helpers namespace has no load-time dependencies: It will lazily load other namespaces as needed, so it does not interfere with fast startup of the REPL itself.

To use these helpers, place a user.clj file on the classpath (in a directory that will not be packaged with your application or library) containing the following:

(ns user
  (:require
   [com.stuartsierra.component.user-helpers :refer [dev go reset]]))

Then, after starting a REPL, you can immediately run one of these functions:

  • (go) or (reset) to load all source code, start the component system running, and switch to the dev namespace.

  • (dev) to just load code and switch to dev without starting the system.

If your develompent namespace is not named dev, you can call set-dev-ns with the (symbol) name of your development namespace:

(ns user
  (:require
   [com.stuartsierra.component.user-helpers 
    :refer [dev go reset set-dev-ns]]))

(set-dev-ns 'com.example.my-app-dev)

Contributions and Forks

I created this library for my own personal use, and I am publishing it in the hopes that others will find it useful. I encourage you to fork and modify this library to suit your own needs and personal workflow, but I am unlikely to merge any changes into this repository.

Copyright and License

MIT License

Copyright (c) 2017 Stuart Sierra

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.