Difference between revisions of "Ruby/C3/Object-Oriented-Programming-Methods/English-timed"

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| | Welcome to this spoken tutorial on '''Object Oriented Programming – Methods '''in '''Ruby'''.
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| | Welcome to this '''spoken tutorial''' on '''Object Oriented Programming – Methods '''in '''Ruby'''.
  
 
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| | In this tutorial we will learn to use:
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| | In this tutorial, we will learn to use:
  
 
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| | '''instance methods'''
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| |* '''instance methods'''
  
 
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| | 00:11
 
| | 00:11
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| |'''class methods'''
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| |* '''class methods'''
  
 
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| | 00:14
 
| | 00:14
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| | '''accessor methods'''
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| |* '''accessor methods'''.
  
 
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| | Here we are using '''Ubuntu '''version 12.04
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| | Here, we are using:
 +
* '''Ubuntu '''version '''12.04'''
  
 
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| | 00:19
 
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| | '''Ruby'''1.9.3
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| |* '''Ruby 1.9.3'''
  
 
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| |You must also have knowledge of '''Linux '''commands, '''Terminal '''and '''Text-editor.'''
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| |You must also have knowledge of '''Linux command'''s, '''Terminal '''and '''Text-editor.'''
  
 
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| | Create a new file in '''gedit '''as shown in the basic level '''Ruby '''tutorials.
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| | Create a new file in '''gedit '''as shown in the basic level '''Ruby tutorials'''.
  
 
|-
 
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| | 01:14
 
| | 01:14
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| |Name it '''instance_methods.rb'''
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| |Name it '''instance_methods.rb'''.
  
 
|-
 
|-
 
| | 01:19
 
| | 01:19
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| | I have a working example of the implementing '''instance methods'''.
+
| | I have a working example of implementing '''instance methods'''.
  
 
|-
 
|-
 
| | 01:24
 
| | 01:24
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| |You can pause the tutorial, and type the code as we go through it.
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| |You can pause the tutorial and type the code as we go through it.
  
 
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| | 01:33
 
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| | I have called an '''initialize method '''to initialize the '''instance variables "name"''' and '''"price"'''.
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| | I have called an '''initialize''' method to initialize the '''instance variables''', "name" and "price".
  
 
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| | 01:41
 
| | 01:41
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| | I have also defined '''instance methods '''named '''"name"''' and '''"price"'''.
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| | I have also defined '''instance methods '''named "name" and "price".
  
 
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| | 01:47
 
| | 01:47
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| |Each of them return '''instance variables "name"''' and '''"price"''' respectively.
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| |Each of them return '''instance variables''' "name" and "price" respectively.
  
 
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| | 01:58
 
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| |Earlier we had studied how to create '''methods '''in '''Ruby'''.
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| |Earlier we had studied how to create methods in Ruby.
  
 
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| | 02:02
 
| | 02:02
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| |Shortly, we will see how these '''methods '''will be available to all '''instances.'''
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| |Shortly, we will see how these methods will be available to all '''instances.'''
  
 
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| | 02:07
 
| | 02:07
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| | Now let us implement the logic we have.
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| | Now, let us implement the '''logic''' we have.
  
 
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| | 02:11
 
| | 02:11
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| | Here, I have initialized a '''Product''' '''object '''and named it as '''product_object_1'''.
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| | Here, I have initialized a '''Product''' object and named it as '''product_object_1'''.
  
 
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| | 02:31
 
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| | Now this '''product instance '''or '''object''' can use the''' instance methods name''' and '''price'''.
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| | Now, this '''product instance '''or '''object''' can use the instance methods '''name''' and '''price'''.
  
 
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| | 02:37
 
| | 02:37
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| |On invoking these '''methods,''' we get the values stored in the '''instance variables'''.
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| |On invoking these methods, we get the values stored in the '''instance variables'''.
  
 
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| | 02:43
 
| | 02:43
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| | Now let us execute this code.
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| | Now, let us '''execute''' this code.
  
 
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| | 03:23
 
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| | Now let us call the '''instance methods "name"''' and '''"price"'''” for this '''object.'''
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| | Now, let us call the '''instance methods- "name" and "price" for this '''object.'''
  
 
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| | 03:35
 
| | 03:35
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| | Next let us switch back to the '''terminal''' and execute the code like before.
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| | Next, let us switch back to the '''terminal''' and execute the code like before.
  
 
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| | Create a new file in '''gedit '''as shown in the basic level '''Ruby '''tutorials.
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| | Create a new file in '''gedit '''as shown in the basic level '''Ruby tutorials'''.
  
 
|-
 
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| | 04:24
 
| | 04:24
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| |Name it '''class_methods.rb'''
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| |Name it '''class_methods.rb'''.
  
 
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| | 04:32
 
| | 04:32
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| |You can pause the tutorial, and type the code as we go through it.
+
| |You can pause the tutorial and type the code as we go through it.
  
 
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| | 04:48
 
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| |I am also using '''class variables''' to hold the values unlike '''instance variables''', earlier.
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| |I am also using '''class variables''' to hold the values, unlike '''instance variables''' earlier.
  
 
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| |Here it is defined using the '''class name "Product"'''.
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| |Here, it is defined using the '''class name "Product"'''.
  
 
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| | Now let us invoke the '''class methods''' as shown here.
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| | Now, let us invoke the '''class methods''' as shown here.
  
 
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| | 05:42
 
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| | Now let us execute the code and inspect the output.
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| | Now, let us execute the code and inspect the output.
  
 
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| | Now you should be able to write your own '''class methods'''.
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| | Now, you should be able to write your own '''class methods'''.
  
 
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| | 06:35
 
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| | Create a new file in '''gedit '''as shown in the basic level '''Ruby '''tutorials.
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| | Create a new file in '''gedit '''as shown in the basic level '''Ruby tutorials'''.
  
 
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| |You can pause the tutorial, and type the code as we go through it.
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| |You can pause the tutorial and type the code as we go through it.
  
 
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| |I have declared '''attr_accessor '''for''' name and price.'''
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| |I have declared '''attr_accessor '''for''' name''' and '''price.'''
  
 
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| | Then, I have set the '''name''' and '''price''' of the '''product object'''.
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| | Then, I have set the '''name''' and '''price''' of the '''product''' object.
  
 
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| | Now let us execute the code like before.
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| | Now let us '''execute''' the code like before.
  
 
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| | In this tutorial we have learnt about:  '''instance methods''',  '''class methods '''and  '''accessor methods'''
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| | In this tutorial, we have learnt about:  '''instance methods''',  '''class methods '''and  '''accessor methods'''.
  
 
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| | 08:06
 
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| | As an assignment:  Define a '''class''' named '''Temperature'''
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| | As an assignment:  define a '''class''' named '''Temperature'''.
  
 
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| | Write an '''instance method '''using '''Ruby's accessor method''' syntax.
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| | Write an '''instance method '''using Ruby's '''accessor method''' syntax.
  
 
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| | The Spoken Tutorial Project Team :
+
| | The Spoken Tutorial project team:
  
 
|-
 
|-
 
| | 08:31
 
| | 08:31
−
| |Conducts workshops using spoken tutorials
+
| |* Conducts workshops using spoken tutorials.
  
 
|-
 
|-
 
| | 08:34
 
| | 08:34
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| |Gives certificates to those who pass an online test
+
| |* Gives certificates to those who pass an online test.
  
 
|-
 
|-
 
| | 08:38
 
| | 08:38
−
| |For more details, please write to contact at spoken hyphen tutorial dot org
+
| |For more details, please write to:
 +
contact at spoken hyphen tutorial dot org.
  
 
|-
 
|-
 
| | 08:44
 
| | 08:44
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| | Spoken Tutorial Project is a part of the Talk to a Teacher project.
+
| | '''Spoken Tutorial''' project is a part of the '''Talk to a Teacher''' project.
  
 
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| | 08:55
 
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| |More information on this Mission is available at: spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
+
| |More information on this mission is available at:
 +
spoken hyphen tutorial dot org slash NMEICT hyphen Intro.
  
 
|-
 
|-
 
| | 09:03
 
| | 09:03
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| | This is Anjana Nair signing off. Thank you
+
| | This is Anjana Nair, signing off. Thank you.
  
 
|}
 
|}

Revision as of 08:34, 30 October 2015

Time Narration
00:01 Welcome to this spoken tutorial on Object Oriented Programming – Methods in Ruby.
00:07 In this tutorial, we will learn to use:
00:09 * instance methods
00:11 * class methods
00:14 * accessor methods.
00:15 Here, we are using:
  • Ubuntu version 12.04
00:19 * Ruby 1.9.3
00:22 To follow this tutorial, you must have a working Internet connection.
00:27 You must also have knowledge of Linux commands, Terminal and Text-editor.
00:31 If not, for relevant tutorials, please visit our website.
00:36 Before we begin, recall that we had created “ttt” directory earlier.
00:41 Let's go to that directory.
00:44 Then to ruby-tutorial.
00:47 Create a directory named oop-methods and cd into it.
00:54 What are Instance methods?
00:56 Instance methods are those methods that are available to all instances of the class.
01:03 Earlier we had studied how to create objects or instances of a class.
01:09 Create a new file in gedit as shown in the basic level Ruby tutorials.
01:14 Name it instance_methods.rb.
01:19 I have a working example of implementing instance methods.
01:24 You can pause the tutorial and type the code as we go through it.
01:29 I have defined a class named Product in this example.
01:33 I have called an initialize method to initialize the instance variables, "name" and "price".
01:41 I have also defined instance methods named "name" and "price".
01:47 Each of them return instance variables "name" and "price" respectively.
01:54 Instance methods are defined just like normal methods.
01:58 Earlier we had studied how to create methods in Ruby.
02:02 Shortly, we will see how these methods will be available to all instances.
02:07 Now, let us implement the logic we have.
02:11 Here, I have initialized a Product object and named it as product_object_1.
02:18 I have initialized it with a name value and a price value.
02:24 The initializer block passes the values to the instance variables @name and @price.
02:31 Now, this product instance or object can use the instance methods name and price.
02:37 On invoking these methods, we get the values stored in the instance variables.
02:43 Now, let us execute this code.
02:46 Switch to the terminal and type: ruby instance_methods.rb and press Enter to see the output.
02:56 You will see that it will print the values you initialized the object with.
03:02 Namely, laptop and 35,000.
03:07 Next, initialize another instance or object.
03:12 Let us name this object product_object_2.
03:18 This time, let us give a different set of values for name and price.
03:23 Now, let us call the instance methods- "name" and "price" for this object.
03:35 Next, let us switch back to the terminal and execute the code like before.
03:41 You will notice that it executes successfully and it prints out the new values.
03:48 This proves that instance methods are available to all objects of the class Product.
03:55 You should now be able to write your own instance methods.
03:59 Next, let us look at what class methods are.
04:04 Class methods are methods available only to the class.
04:09 These methods are not available to instances of the class.
04:14 There are different ways you can define class methods.
04:16 Let us look at an example.
04:18 Create a new file in gedit as shown in the basic level Ruby tutorials.
04:24 Name it class_methods.rb.
04:28 I have a working example of class methods.
04:32 You can pause the tutorial and type the code as we go through it.
04:36 I have defined a Product class like before.
04:40 I have also called an initializer like before.
04:44 However, this time I have added an extra argument called description.
04:48 I am also using class variables to hold the values, unlike instance variables earlier.
04:55 This class will demonstrate to you the 3 different ways one can define class methods.
05:01 Checkout the class method declaration for name.
05:06 Here, it is defined using the class name "Product".
05:10 Then, checkout the second class methods declaration.
05:14 Here I have used the "self" keyword.
05:18 Next, checkout the third way you can define class methods.
05:23 Now let us implement these class methods.
05:27 Let us first initialize an object of Product, like before.
05:32 This time we are also giving a value for the description.
05:37 Now, let us invoke the class methods as shown here.
05:42 Now, let us execute the code and inspect the output.
05:47 Switch to the terminal and execute the code like before.
05:54 You will notice that it will print the values for name, price and description.
05:59 Now, you should be able to write your own class methods.
06:03 Next we shall see what accessor methods are.
06:07 Ruby uses accessor methods to access data defined within classes.
06:13 Accessor methods comprise of setter methods and getter methods.
06:18 Setter methods set the values.
06:22 Getter methods get those values.
06:24 Ruby uses the word attr_accessor to declare these methods.
06:31 Let us look at an example of accessor methods.
06:35 Create a new file in gedit as shown in the basic level Ruby tutorials.
06:39 Name it accessor_methods.rb
06:43 I have a working example of the implementing accessor methods.
06:47 You can pause the tutorial and type the code as we go through it.
06:52 I have defined a class named Product, in this example.
06:56 I have declared attr_accessor for name and price.
07:01 That is all that is required to use these types of methods.
07:05 Now let us put it to action.
07:07 I have initialized a Product object.
07:10 Then, I have set the name and price of the product object.
07:14 This is possible because the attr_declaration, by default, creates methods for setting values.
07:22 I have then attempted to print the values using the getter methods for name and price.
07:28 These getter methods were also generated by the declaration of attr_accessor.
07:35 Now let us execute the code like before.
07:40 You will notice that it prints the values that were set.
07:44 By now, you should be able to write your own accessor methods.
07:50 One thing to note is that accessor methods are, by default, instance methods.
07:55 Thus they can be accessed by different instances of the class Product.
08:00 In this tutorial, we have learnt about: instance methods, class methods and accessor methods.
08:06 As an assignment: define a class named Temperature.
08:10 Write an instance method using Ruby's accessor method syntax.
08:15 This method should calculate the Celsius for the given Fahrenheit.
08:20 Watch the video available at the following link.
08:23 It summarizes the Spoken Tutorial project.
08:26 If you do not have good bandwidth, you can download and watch it.
08:30 The Spoken Tutorial project team:
08:31 * Conducts workshops using spoken tutorials.
08:34 * Gives certificates to those who pass an online test.
08:38 For more details, please write to:

contact at spoken hyphen tutorial dot org.

08:44 Spoken Tutorial project is a part of the Talk to a Teacher project.
08:48 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
08:55 More information on this mission is available at:

spoken hyphen tutorial dot org slash NMEICT hyphen Intro.

09:03 This is Anjana Nair, signing off. Thank you.

Contributors and Content Editors

PoojaMoolya, Sandhya.np14

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