jimweirich

class Parent
  class << self
    def children
      @children ||= []
    end
    def inherited(cls)
      children << cls
    end
  end
end

jimweirich

module ConcernedParent
  module ClassMethods
    def children
      @children ||= []
    end
    def inherited(cls)
      children << cls
    end
  end
  def self.included(cls)

jimweirich

(defn reject-multiples
  "A function that rejects multiples of n."
  [n]
  (fn [x] (not (zero? (mod x n)))))

(defn primes
  "An infinite sequence of prime numbers"
  ([] (primes (iterate inc 2)))
  ([seq]
   (let [head (first seq)]

jimweirich

RUBY = File.join(
    Config::CONFIG['bindir'],
    Config::CONFIG['ruby_install_name'] + Config::CONFIG['EXEEXT']).
    sub(/.*\s.*/m, '"\&"')

jimweirich

%w(some_method some_other_method).each do |method|
  it "should call #{method}" do
    obj.should_receive(:some_method).once
    test_code_here
  end
end

jimweirich

[Object|should_receive();new_instances();flexmock_get();flexmock_teardown();flexmock_verify()]
[Object]obj<->flexmock_proxy[PartialMockProxy|should_receive()]
[PartialMockProxy]->mock[Mock|should_receive()]
[Object]<-[note:These 5 methods are dynamically added to a partially mocked object]
[PartialMockProxy]<-[note:Proxies mediate between the mock and object]
[Mock]<-[note:Regular mock object.  Knows nothing about proxies or real object.]

jimweirich

;; Exercise 1.1.  Below is a sequence of expressions. What is the
;; result printed by the interpreter in response to each expression?
;; Assume that the sequence is to be evaluated in the order in which
;; it is presented.

;; 10
;; => 10

;; (+ 5 3 4)
;; => 12

jimweirich

;; SICP 1.4
;;
;; Exercise 1.4.  Observe that our model of evaluation allows for
;; combinations whose operators are compound expressions. Use this
;; observation to describe the behavior of the following procedure:

(define (a-plus-abs-b a b)
  ((if (> b 0) + -) a b))

;; (a-plus-abs-b 2 3)

jimweirich

;; Exercise 1.8.  Newton's method for cube roots is based on the fact
;; that if y is an approximation to the cube root of x, then a better
;; approximation is given by the value
;;
;; Use this formula to implement a cube-root procedure analogous to
;; the square-root procedure. (In section 1.3.4 we will see how to
;; implement Newton's method in general as an abstraction of these
;; square-root and cube-root procedures.)

;; ANSWER ------------------------------------------------------------

jimweirich

;; SICP Exercise 1.2:

;; Translate the following expression into prefix form

(/ (+ 5 4 (- 2 (- 3 (+ 6 (/ 1 5)))))
   (* 3 (- 6 2) (- 2 7)) )

;; => -71/300
;;    or -0.236666666666667