The basic idea

For a function, take it's arguments as dependencies, which will be injected automatically by the framework. And the return map as values it can provie to the injection context.

Eg:

(defn a-fun [{:keys [db-port db-url]}]
  {:db-connection some-conn})

For this demo function, it means that give a db-port and a db-url, it will generate connection, and this connection can be injected by other functions with db-connection

How to use

Baic usage

(require '[com.github.clojure.di.core :refer [defdi execute]])

(defdi http-server [{:keys [http-port route]
                     db-conn :db-connection}]
  ;start http server
  {:http-server xxx})

(defdi database [{:db/keys [url port user password]}]
  ; create db connection
  {:db-connection the-connection}）

;; other di
(defdi ...)

;;then run the di by
(execute [http-server database ...])

defdi has the same syntax as defn, and returns a normal function just as defn, except

1. It must have exactly one or zero argument
2. It must return a map with keyword as keys

Then by run (execute [http-server database ...]), it will calculate the dependency graph, and excute the di functions one by one with their dependency order

Use bootstrap

For convenience, this library also provide a bootstrap function, to help you bootstrap you application

(require '[com.github.clojure.di.app :refer [bootstrap]])

(bootstrap "com.example")

Then, the libary will scan all the namespace in the classpath which has the prefix com.example, and collect all the di component defined by defdi, and excute them.

Thus, you don't need to care about where to import the depenedency, just let the library to handle it

For more detail usage, refer the tests