The basic idea

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

For this function, it is known that given db-port and db-url it will given back a db-connection. We can use clojure macro to parse these information

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 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