CMSI 386 QUIZ 1 ANSWERS
=======================

PROBLEM 1
---------

class Account
  def initialize(id)
    @id = id
    @balance = 0
  end
  attr_reader :id, :balance
  def balance=(balance)
    if (balance < 0)
      puts "overdrafts not allowed"
    else
      difference = balance - @balance
      action = difference < 0 ? "withdrew from" : "deposited to"
      @balance = balance
      puts "#{difference.abs} #{action} account #{@id}"
    end
  end
end

PROBLEM 2
---------

/**
 * This version does not prevent the balance property from being
 * accessed directly.  You will learn how to do this later in class.
 * Also, the "side effect" here is really lame: it alerts!
 */
function Account(id) {
    this.id = id;
    this.balance = 0;
}
Account.prototype.setBalance = function (balance) {
    if (balance < 0) {
        alert("overdrafts not allowed");
    } else {
        var difference = balance - this.balance;
        var action = difference < 0 ? "withdrew from" : "deposited to";
        this.balance = balance;
        alert(Math.abs(difference) + " " + action + " account #" + this.id);
    }
    return balance; // To make it just like Ruby
}

PROBLEM 3
---------

After the script is run, b is [10,10,10,10,10,10,10,10,10,10].
Ten distinct function objects are created.  In each the body
has a return statement that will return the value of i.  In JavaScript
whenever you refer to a variable in an expression, you look up the
value of the variable right then and there.  Each of the functions
refer to the variable called i.  By the time these functions are called
the value of i is 10.

PROBLEM 4
---------

def some_nonsense_exam_method(p, a)
  i = -1
  a.collect do |x|
    (i += 1).times {x = p[x]}
    x
  end
end


PROBLEM 5
---------

function someNonsenseExamMethod(f, a) {
    var result = [];
    for (var i = 0; i < a.length; i += 1) {
        var x = a[i];
        for (var j = 0; j < i; j += 1) {
            x = f(x);
        }
        result.push(x);
    }
    return result;
}