Lazy maps for Clojure. Useful as a dependency injection container, and for other purposes.
A rough port of yadic to Clojure, with thanks to Dan Bodart for the original idea and implementation.
yadic is similar in some ways to Component
The main differences are:
- Construction is lazy
- Decoration is supported as a first-class concept
- We can support components with dependencies that are not defined at compile time
AutoCloseablecomponents are closed by default, without additional coding- Container/system is not a persistent data structure
- Less boilerplate. i.e. no
(start [this] (assoc this :some-component-key (some-component-constructor some-dependency)) - The concepts of constructor definitions (System/Component or Activators in yadic) and a container of the instances created by the Activators/Components are decomplected
- Systems/Containers can be scope- we support having a application-scoped set of dependencies, which are then used by components in an application-scoped System/Container
Finally, and most importantly, yadic is intended to be a more general library than Component. This is demonstrated by the drop-in replacement for Component, impemented with yadic and the drop-in replacement for Prismatic's excellent Graph library (see section below).
Lazy instantiation means we can use a complete system definition without worrying about the overhead of instantiating components which we will not use.
We find decoration to be extremely useful for separating concerns. We often build up. Compojure middleware
Copyright © 2015 Matthew Savage
Distributed under the MIT license http://opensource.org/licenses/MIT