learn_ruby_ch2_pt5

Question 1

User alias (greet, ahello)

Answer 1

def greet
puts “hello”
end

alias ahello greet

ahello

Question 2

A block to iterate through pacific

Answer 2

A block in Ruby is more than just a code block or group of statements

pacific = [ “Washington”, “Oregon”, “California” ]
pacific.each do |element|
puts element
end

or

pacific.each { |e| puts e }

Question 3

Use yield to run a block of code (gimme)

Answer 3

def gimme
  if block_given?
    yield
  else
    puts "I'm blockless!"
  end
end

gimme { print “Say hi.” } # => Say hi.

gimme # => I’m blockless!

Question 4

Use proc and lambda

count, your_proc, my_proc

Answer 4

!/usr/bin/env ruby

count = Proc.new { [1,2,3,4,5].each do |i| print i end; puts }
your_proc = lambda { puts "Lurch: 'You rang?'" }
my_proc = proc { puts "Morticia: 'Who was at the door, Lurch?'" }

# What kind of objects did you just create?
puts count.class, your_proc.class, my_proc.class

Calling all procs
count.call
your_proc.call
my_proc.call

Question 5

create a symbol

name = “Matz”

Answer 5

symbols are like placeholders for identifiers and strings

name = “Matz”
name.to_sym # => :Matz
:Matz.id2name # => “Matz”
name == :Matz.id2name # => true

Symbol.all_symbols # about 1000 symbols

Question 6

Get info on print in the ruby kernel

Answer 6

ri Kernel.print

requires ruby-doc.noarch