chrismo

As the domain logic gets more complicated and you begin moving toward a
rich Domain Model (116), the simple approach of an Active Record (160)
starts to break down. The one-to-one match of domain classes to tables
starts to fail as you factor domain logic into smaller classes.
Relational databases don't handle inheritance, so it becomes difficult
to use strategies [Gang of Four] and other neat OO patterns. As the
domain logic gets feisty, you want to be able to test it without having
to talk to the database all the time.

Fowler, Martin (2002-11-05). Patterns of Enterprise Application

chrismo

Coloured fox fur production, HOPEDALE, Labrador, 1834-1842
#Source: C. Elton (1942) "Voles, Mice and Lemmings", Oxford Univ. Press
#Table 17, p.265--266
      29
      22
       2
      16
      12
      35
       8

chrismo

(fn [coll x]
  (apply concat
         (map
           (fn [item]
             (map
               (fn [_] identity item)
               (range x)))
           coll)))

chrismo

(fn [x coll]
  (keep #(if (= (count %) x) % nil)
        (map #(map last %)
             (vals
               (group-by
                 #(quot (first %) x)
                 (map-indexed #(vector % %2) coll)))))
  )

chrismo

module Car
  def vroom
    '<car noise>'
  end
end

module Boat
  def vroom
    '<boat noise>'
  end

chrismo

# converted to stand-alone script

require 'minitest/autorun'
require 'minitest/unit'
require 'stringio'

# fake out the logger
class Rails
  @@logger = StringIO.new

chrismo

  If file exists in both places:

    git diff target_branch source_branch relative_path_to_file | git apply

  If file is new on other branch:

    git checkout source_branch relative_path_to_file


The checkout will work even if the file exists, and will stomp it, 

chrismo

Open git history for the file.
In annotate view, find the line of code and the sha.
Select history view and start typing the sha until it's selected.
Type 'esc', then down arrow.
Right-click and select "Annotate" - this will open the prior rev in the editor in annotate view.
Find that line of code and repeat.

chrismo

child = fork do
  at_exit { $stderr.puts "Child one is done." }
  exit # superfluous
end
Process.wait
$stderr.puts "Parent is done waiting for child one #{child}."

child = fork do
  at_exit { $stderr.puts "This won't get hit." }
  exit!

chrismo

18930: Parent
18933: Child A
18934: Child B
18933: END in child if only exit called
18933: at_exit in child if only exit called
18933: parent END (only one)
18933: parent at_exit (2 times)
18933: parent at_exit (2 times)
18930: parent: child died
18930: parent trap(0)