Nesting and a little Proc.

Zed Shaw wrote a great tutorial on Ruby. Going through it now, I always like going through these things, because experienced programmers might slip up and give me something useful:

 puts "ADDING #{a} + #{b}"
  a + b
end

def subtract(a, b)
  puts "SUBTRACTING #{a} - #{b}"
  a - b
end

def multiply(a, b)
  puts "MULTIPLYING #{a} * #{b}"
  a * b
end

def divide(a, b)
  puts "DIVIDING #{a} / #{b}"
  a / b
end

Novice:

puts "Let's do some math with just functions!"

age = add(30, 5)
height = subtract(78,4)
weight = multiply(90, 2)
iq = divide(100, 2)

Programmer:

puts "Age: #{age}, Height: #{height}, Weight: #{weight}, IQ: #{iq}"

# A puzzle for the extra credit, type it in anyway.
puts "Here is a puzzle."

what = add(age, subtract(height, multiply(weight, divide(iq, 2))))

puts "That becomes: #{what} Can you do it by hand?"

Hacker (of course my own spin):

the_multiplier = Proc.new {|a, *b| b.collect {|i| i*a }}

puts “Maybe you could’ve done that nested thing by hand… But if you got this right: #{the_multiplier.call(what,50,2,31)}, then you’ve impressed me”