(ns mytask
  (:require [dire.core :refer [with-handler!]]))

;;; Define a task to run. It's just a function.
(defn divider [a b]
  (/ a b))

;;; For a task, specify an exception that can be raised and a function to deal with it.
(with-handler! #'divider
  "Here's an optional docstring about the handler."
  java.lang.ArithmeticException
  ;;; 'e' is the exception object, 'args' are the original arguments to the task.
  (fn [e & args] (println "Cannot divide by 0.")))

(divider 10 0) ; => "Cannot divide by 0."

(ns mytask
  (:require [dire.core :refer [with-handler! with-finally!]]))

;;; Define a task to run. It's just a function.
(defn divider [a b]
  (/ a b))

(with-handler! #'divider
  java.lang.ArithmeticException
  (fn [e & args] (println "Catching the exception.")))

(with-finally! #'divider
  "An optional docstring about the finally function."
  (fn [& args] (println "Executing a finally clause.")))

(divider 10 0) ; => "Catching the exception.\nExecuting a finally clause.\n"

(ns mytask
  (:require [dire.core :refer [with-precondition! with-handler!]]))

(defn add-one [n]
  (inc n))

(with-precondition! #'add-one
  "An optional docstring."
  ;;; Name of the precondition
  :not-two
  (fn [n & args]
    (not= n 2)))
    
(with-handler! #'add-one
  {:precondition :not-two}
  (fn [e & args] (apply str "Precondition failure for argument list: " (vector args))))

(add-one 2) ; => "Precondition failure for argument list: (2)"

(ns mytask
  (:require [dire.core :refer [with-postcondition! with-handler!]]))

(defn add-one [n]
  (inc n))

(with-postcondition! #'add-one
  "An optional docstring."
  ;;; Name of the postcondition
  :not-two
  (fn [n & args]
    (not= n 2)))
    
(with-handler! #'add-one
  {:postcondition :not-two}
  (fn [e result] (str "Postcondition failed for result: " result)))

(add-one 1) ; => "Precondition failure for reault: (2)"

(ns mydire.prehook
  (:require [dire.core :refer [with-pre-hook!]]))

(defn times [a b]
  (* a b))

(with-pre-hook! #'times
  "An optional docstring."
  (fn [a b] (println "Logging something interesting.")))

(times 21 2) ; => "Logging something interesting."

(ns mydire.prehook
  (:require [dire.core :refer [with-eager-pre-hook!]]))

(defn times [a b]
  (* a b))

(with-eager-pre-hook! #'times
  "An optional docstring."
  (fn [a b] (println "Logging something before preconditions are evaluated.")))

(times 21 2) ; => "Logging something before preconditions are evaluated."

(ns mytask
  (:require [dire.core :refer [with-handler supervise]]))

;;; Define a task to run. It's just a function.
(defn divider [a b]
  (/ a b))

;;; For a task, specify an exception that can be raised and a function to deal with it.
(with-handler #'divider
  "An optional docstring."
  java.lang.ArithmeticException
  ;;; 'e' is the exception object, 'args' are the original arguments to the task.
  (fn [e & args] (println "Cannot divide by 0.")))

(with-handler #'divider
  java.lang.NullPointerException
  (fn [e & args] (println "Ah! A Null Pointer Exception! Do something here!")))

;;; Invoke with the task name and it's arguments.
(supervise #'divider 10 0)   ; => "Cannot divide by 0."
(supervise #'divider 10 nil) ; => "Ah! A Null Pointer Exception! Do something here!"

(ns mytask
  (:require [dire.core :refer [with-handler supervise]]
            [fs.core :refer [touch]]))

(defn read-file [file-name]
  (slurp file-name))

(with-handler #'read-file
  java.io.FileNotFoundException
  (fn [exception file-name & _]
    (touch file-name)
    (supervise #'read-file file-name)))

(supervise #'read-file "my-file")

(defn add-one [n]
  (inc n))

(with-handler #'add-one
  java.lang.NullPointerException
  (fn [e & args] (println "Catching the exception.")))

(with-finally #'add-one
  (fn [& args] (println "Executing a finally clause.")))

(with-out-str (supervise #'add-one nil)) ; => "Catching the exception.\nExecuting a finally clause.\n"

(defn add-one [n]
  (inc n))

(with-precondition #'add-one
  ;;; Name of the precondition
  :not-two
  (fn [n & args]
    (not= n 2)))

(with-handler #'add-one
  ;;; Pair of exception-type (:precondition) to the actual precondition (:not-two)
  {:precondition :not-two}
  (fn [e & args] (apply str "Precondition failure for argument list: " (vector args))))

(supervise #'add-one 2) ; => "Precondition failure for argument list: (2)"

(defn add-one [n]
  (inc n))

(with-postcondition #'add-one
  :not-two
  (fn [n & args]
    (not= n 2)))

(with-handler #'add-one
  {:postcondition :not-two}
  (fn [e result] (str "Postcondition failed for result: " result)))

(supervise #'add-one 1) ; => "Postcondition failed for result: 2"

(defn times [a b]
  (* a b))

(with-pre-hook #'times
  (fn [a b] (println "Logging something interesting."))

(supervise #'times 1 2) ; => "Logging something interesting.", 2

(defn times [a b]
  (* a b))

(with-eager-pre-hook #'times
  "An optional docstring."
  (fn [a b] (println "Logging something before preconditions are evaluated.")))

(supervise #'times 21 2) ; => "Logging something before preconditions are evaluated."