21.4. Libraries and Common Examples

dir = Dir.new("dir")
entries = []
dir.each { |file| entries << file }

assertEquals([".", ".."], entries)

entries = []
Dir.foreach("dir") do |file|
  if file[0..0] != "."
    entries << file
  end
end
assertEquals([], entries)

#!/usr/bin/env ruby
  l = []
  l << "bla"

x = ""
for i in 0..5 do x += i.to_s end
assertEquals("012345", x)

x = ""
i = 0
begin
  x += i.to_s
  i += 1
end while i <= 5
assertEquals("012345", x)

x = ""
i = 0
while i <= 5
  x += i.to_s
  i += 1
end
assertEquals("012345", x)

# Can we handle classes as objects? Yes
x = Address
a = x.new("Elfgenweg 14", "Duesseldorf")
print a, "\n"

assertEquals("Germany", a.country)

#----------------------------------------------------------------------
# blocks and iterators

s = ""
(0..5).each { |i| s += i.to_s }
assertEquals("012345", s)

s = ""
(0..5).to_a.reverse_each { |i| s += i.to_s }
assertEquals("543210", s)

assertEquals([2, 4], [1, 2].collect {|i| 2 * i})

#----------------------------------------------------------------------
# Scoping

def testScope()
  # As in python, "if" statements do not define a new scope
  if 1
    innerX = 5
  end
  assertEquals(5, innerX)

  # The same is true for loops
  for i in [1, 2] do
    innerY = 6
  end
  assertEquals(6, innerY)
end

testScope()

#----------------------------------------------------------------------
# Function "pointers"
#
# The function "proc" converts a block into a function (Proc) object.
# This includes the context (here the variable x).

class Button
  def initialize(label, action)
    @label = label
    @action = action
  end

  def press
    @action.call()
  end
end

x = "this is "
b = Button.new("bla", proc { x + "blub" })
assertEquals("this is blub", b.press)

#----------------------------------------------------------------------
#