Week7 home work

week1/homework/.rspec

@@ -0,0 +1,2 @@
+--color
+--format nested

week1/homework/questions.txt

@@ -3,13 +3,34 @@ Chapter 3 Classes, Objects, and Variables
 p.86-90 Strings (Strings section in Chapter 6 Standard Types)
 
 1. What is an object?
+Object is an instance of a class having:
+a. Unique internal state
+b. Attributes that expose internal state to external world
+c. Methods using which one can interact with Object and read/change the internal state.
 
 2. What is a variable?
+variable is a placeholder/identifier of data.
 
 3. What is the difference between an object and a class?
+class defines an object/class of objects.
+When I create an object, I create an instance of a class that defines the object.
 
 4. What is a String?
 
+String is a sequence of characters represented as a single entity. 
+
 5. What are three messages that I can send to a string object? Hint: think methods
 
+a. String.eql?(another_string) : Tests the equality of two strings.
+b. String.clear : Empties the string
+c. String.length : Returns the length of the string
+
 6. What are two ways of defining a String literal? Bonus: What is the difference between them?
+
+A String literal can be defined in the following ways:
+
+a. Using single-quote .i.e singleQuotedStr = 'This is a single quoted string'. This can also be done like singleQuotedStr = %q{This is a single quoted string}
+b. Using double-quote .i.e doubleQuotedStr = "This is a double quoted string". This can also be done like doubleQuotedStr = %Q{This is a double quoted string}
+
+Double-quoted string allows variables to be inserted into it and interpretd at run time. This is not possible with single-quoted strings.
+

week1/homework/strings_and_rspec_spec.rb

@@ -10,17 +10,23 @@
 describe String do
 	context "When a string is defined" do
 		before(:all) do
-			@my_string = "Renée is a fun teacher. Ruby is a really cool programming language"
+			@myString = "JayaPrakash likes programming and mystery novels"
 		end
-		it "should be able to count the charaters"
-		it "should be able to split on the . charater" do
-			pending
-			result = #do something with @my_string here
-			result.should have(2).items	
+		it "should be able to count the charaters" do
+			(@myString.length).should eq 48
+		end
+		it "should be able to split on the ' ' charater" do
+			result = @myString.split(' ')
+			result.should have(6).items	
 		end
 		it "should be able to give the encoding of the string" do
-			pending 'helpful hint: should eq (Encoding.find("UTF-8"))'
+			(@myString.encoding).should_not eq nil
+			(@myString.encoding.to_s).should eq "UTF-8"
+			(@myString.encoding).should eq Encoding.find("UTF-8")
+			@myString = @myString.force_encoding(Encoding.find("ASCII-8BIT"))
+			(@myString.encoding).should eq Encoding.find("ASCII-8BIT")
+			(@myString.encoding).should_not eq Encoding.find("UTF-8")
+			(@myString.encoding == Encoding.find("UTF-8")).should eq false
 		end
 	end
 end
-

week1/ruby_spec.rb

@@ -1,7 +1,7 @@
-describe "Playing With Ruby! " do
-	context 'when adding numbers' do
-		it "should add numbers" do
-			(2+2).should eq 4
-		end
-	end		
+describe "Playing With Ruby! " do
+	context 'when adding numbers' do
+		it "should add numbers" do
+			(2+2).should eq 4
+		end
+	end
 end

week2/homework/.rspec

@@ -0,0 +1,2 @@
+--color
+--format nested

week2/homework/questions.txt

@@ -4,10 +4,25 @@ Sharing Functionality: Inheritance, Modules, and Mixins
 
 1. What is the difference between a Hash and an Array?
 
+Hash is indexed on objects where as Array is indexed on integers. 
+
 2. When would you use an Array over a Hash and vice versa?
 
+I would use an Array to maintain a collection of similar objects, where as a Hash for dissimilar ones.
+
 3. What is a module? Enumerable is a built in Ruby module, what is it?
 
+Module defines a namespace, grouping together methods, constants and classes, which can
+be mixed-in into other classes.
+
+Enumerable is mixin that provides sorting, searching and traversal functionality.
+
 4. Can you inherit more than one thing in Ruby? How could you get around this problem?
 
+A class can have only one parent. But we can inherit the behavior of more than one thing by using mixins. 
+
 5. What is the difference between a Module and a Class?
+
+Module can't be instantiated like a Class. Multiple module can be included in a class, where as only
+one class can be inherited by other.
+

week2/homework/simon_says.rb

@@ -0,0 +1,35 @@
+module SimonSays
+
+def echo(str)
+	str
+end
+
+def shout(str)
+	str.upcase
+end
+
+def repeat(*args)
+	str = nil
+	count = 2
+	if (!args[0].nil?)
+		str = args[0]
+	end
+	if (!args[1].nil?)
+		count = args[1]
+	end
+	repeatedStr = String.new(str)
+	while (count > 1) do
+		count = count - 1
+		repeatedStr.concat(" ".concat(str))
+	end
+	repeatedStr
+end
+
+def start_of_word(str, count)
+	str[0...count]
+end
+
+def first_word(str)
+	str.split[0]
+end
+end

week3/exercises/book.rb

@@ -1,7 +1,29 @@
-class Book
+$global_hello = "hi there"
 
-  def pages
-
-  end
+module Library
+  class Book
+    HELLO = "hello I shouln't change..."
+
+    attr_accessor :pages, :title
+
+    @@library_count = 0
+
+    def self.library_count
+      @@library_count
+    end
+
+    def initialize pages = 0, title = "N/A"
+      @pages = pages
+      @title = title
+      @@library_count += 1
+    end
 
+
+    def happy
+      $global_hello = "hello"
+      "There are #{@pages} happy pages in this book"
+    end
+
+
+  end
 end

week3/exercises/book_spec.rb

@@ -1,10 +1,33 @@
 require './book.rb'
 
 describe Book do
-
-  it "should have a pages" do
-    book = Book.new
-    book.should respond_to "pages"
+
+  before :each do
+    @book = Book.new 542, "Programming Ruby"
+  end
+
+  context "::library_count" do
+    it "should tell us how many books are in our library" do
+      34233.times{ Book.new }
+      Book.library_count.should eq 34234
+    end
   end
 
+  context "#pages" do
+    it "should have a pages" do
+      @book.should respond_to "pages"
+    end
+
+    it "should allow us to get the number of pages" do
+      @book.pages.should eq 542
+    end
+  end
+
+  context "#title" do
+    it "should let us read the title" do
+      @book.title.should eq "Programming Ruby"
+    end
+  end
+
+
 end

week3/exercises/human.rb

@@ -0,0 +1,6 @@
+require_relative 'named_thing'
+require_relative 'other_thing'
+class Human
+  include NamedThing
+  include OtherThing
+end

week3/exercises/monster.rb

@@ -11,4 +11,10 @@ def initialize(noc, legs, name="Monster", vul = [], dangers = [])
 		@dangers = dangers
 		@legs = legs
 	end
+
+	def attack! human
+    puts "hi from Monster"
+    super
+  end
+
 end	

week3/exercises/other_thing.rb

@@ -0,0 +1,5 @@
+module OtherThing
+  def say_name
+    "hello"
+  end
+end

week3/exercises/vampire.rb

@@ -1,6 +1,14 @@
 require './monster.rb'
 class Vampire < Monster
 	def initialize(noc=true, legs=2, name ="Vampire", vul=[:garlic, :sunlight], dangers=[:bites])
-		super(noc,legs,name,vul,dangers)
+		super
 	end
+
+
+
+  def attack! human
+    puts "hi from Vampire"
+  end
+
+
 end

week3/exercises/zombie.rb

@@ -0,0 +1,8 @@
+require_relative 'named_thing'
+class Zombie
+  include NamedThing
+
+  def say_name
+    "uuurrrggghhhh #{@name}"
+  end
+end

week3/homework/.rspec

@@ -0,0 +1,2 @@
+--color
+--format nested

week3/homework/calculator.rb

@@ -0,0 +1,20 @@
+class Calculator
+
+def sum input
+	input.inject(0,:+)
+end
+
+def pow base, exponent
+	base**exponent
+end
+
+def multiply *input
+	input.flatten.inject(1,:*)
+end
+
+def fac input
+	input = 1 if input == 0
+	(1..input).to_a.inject(:*)
+end
+
+end

week3/homework/calculator_spec.rb

@@ -18,10 +18,18 @@
     it "computes the sum of an array of two numbers" do
       @calculator.sum([7,11]).should == 18
     end
+
+    it "computes the sum of an array of floating point numbers" do
+      @calculator.sum([7.1,11.5]).should == 18.6
+    end
 
     it "computes the sum of an array of many numbers" do
       @calculator.sum([1,3,5,7,9]).should == 25
     end
+
+    it "computes the sum of an array of with negative numbers numbers" do
+      @calculator.sum([1,3,5,7,-100]).should == -84
+    end
   end
 
   # Once the above tests pass, 
@@ -31,6 +39,10 @@
 		@calculator.multiply(2,2).should eq 4
 	end
 
+    it "multiplies an empty array of numbers" do
+    @calculator.multiply([]).should eq 1
+    end
+
   	it "multiplies an array of numbers" do
 		@calculator.multiply([2,2]).should eq 4
   	end

week3/homework/questions.txt

@@ -6,10 +6,39 @@ Please Read:
 
 1. What is a symbol?
 
+Symbol is a constant, that uniquely identifies string of characters (named thing). It is respresented as a colon followed by a string of characters.
+
 2. What is the difference between a symbol and a string?
 
+Since symbol is a constant its value/content can't be changed, where as a string content can be changed. Also a symbol is created only once irrespective of how many times we use it, where as a string is created multiple times if used at multiple places.
+
 3. What is a block and how do I call a block?
 
+Block is one or more lines of code enclosed in braces or keywords do and end. Block passed to a method can be invoked by using "yield" statement inside method definition.
+
 4. How do I pass a block to a method? What is the method signature?
 
+A block is passed to a method, by defining it immediately after the method invocation. If there are parameters to the method, then block should be defined after the parameters are specified.
+
+def method1
+...
+end
+
+method1 { "block that would be passed to method 1" } 
+
+def method2 (para1, para2)
+...
+end
+
+method2 (a, b) do 
+	"block that would" \
+		"be passed to method2"
+end 
+
 5. Where would you use regular expressions?
+
+Regular expression is a string of characters that defines a pattern. The patterns are used:
+
+ a. To test if a string or part of a string matches the pattern
+ b. To extract information from a string that matches the given pattern
+ c. To change (.i.e substitue/delete) sections within a string that matches the pattern

week4/homework/.rspec

@@ -0,0 +1,3 @@
+--color
+--color
+--format nested