systems.thoughtfull.amalgam — systems.thoughtfull/amalgam 2.2.0

configure clj

(configure component config)

(configure component config merge-fn)

Recursively merge config map into component using merge-fns as necessary. Maps are recursively merged. Sets, vectors and lists are non-recursively concatenated.

This behavior can be overridden with merge-fns, which should match the structure of config and value. A merge function takes two arguments: the current value, and the configured value (respectively) and should return the final, resolved value.

Example:

user> (amalgam/configure {:a [1] :b {:c [2]}}
        {:a [10] :b {:c [20] :d 30}}
        {:b {:c amalgam/overwrite}})
{:a [1 10], :b {:c [20], :d 30}}

make-component-fn clj

(make-component-fn & {:keys [start stop]})

Make a component constructor that takes options as keyword args and returns a component.

After this component has been started, stopping it resets it back to the options map. In other words,

(let [make-component (make-component-fn ...)
      c (make-component ...)]
  (assert (identical? c (component/stop (component/start c)))))

• start — (optional) a single argument function taking the options and returning a new instance of the component. The return value of start should be able to take metadata.
• stop — (optional) a single argument function taking the component and releasing resources. stop is side-effecting and its return value is ignored.

Example:

(def temp-file
  (amalgam/make-component-fn
    :start (fn [this] (assoc this :file (io/file (:path this))))
    :stop (fn [this] (io/delete-file (:file this) true))))
(def my-system (component/system-map :scratch-file (temp-file :path "/tmp/scratch")))

overwrite clj

(overwrite _v c)

Resolve current and configuration values by always taking the configuration value.

run-system clj

(run-system make-system read-config)

(run-system make-system read-config merge-fns)

Start a configured system and run it until the JVM exits.

• make-system — no argument function returning a new system
• read-config — no argument function returning the configuration map. The configuration map should mirror the structure of the system.
• merge-fns (optional) — map mirroring the structure of both the system and configuration maps that contains merge functions to resolve a final value from the current value and configured value.

See configure start-system

start-system clj

(start-system make-system read-config)

(start-system make-system read-config merge-fns)

Construct, configure, then start a system.

• make-system — no argument function returning a new system
• read-config — no argument function returning the configuration map. The configuration map should mirror the structure of the system.
• merge-fns (optional) — map mirroring the structure of both the system and configuration maps that contains merge functions to resolve a final value from the current value and configured value.

Example:

user> (amalgam/start-system #(component/system-map :component (map->Component {:foo :bar}))
        (constantly {:component {:foo :baz}})
        {:component {:foo amalgam/overwrite}})
{:component {:foo :baz}}

See configure