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ngm's solution

to Two Fer in the Emacs Lisp Track

Published at Apr 24 2019 · 0 comments
Test suite


This exercise has changed since this solution was written.

Two-fer or 2-fer is short for two for one. One for you and one for me.

"One for X, one for me."

When X is a name or "you".

If the given name is "Alice", the result should be "One for Alice, one for me." If no name is given, the result should be "One for you, one for me."



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;;; two-fer-test.el --- Tests for Two-fer (exercism)

;;; Commentary:
;; Common test data version: 1.2.0 4fc1acb

;;; Code:

(load-file "two-fer.el")

(ert-deftest no-name-given ()
  (should (equal (two-fer) "One for you, one for me.")))

(ert-deftest a-name-given ()
  (should (equal (two-fer "Alice") "One for Alice, one for me.")))

(ert-deftest another-name-given ()
  (should (equal (two-fer "Bob") "One for Bob, one for me.")))

(provide 'two-fer-test)

;;; two-fer-test.el ends here
;;; two-fer.el --- Two-fer Exercise (exercism)

;;; Commentary:
;;; Use local variable for name.
;;; Use or macro for checking whether passed name argument has a value.

;;; Code:
(defun two-fer (&optional name)
  (let ((name (or name "you")))
    (format "One for %s, one for me." name)))

(provide 'two-fer)
;;; two-fer.el ends here

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ngm's Reflection

I learned from my mentor to use `let` to scope variables locally (as opposed to setq which I was using previously). I also learned the `or` macro as an alternative to an if conditional.