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Ruby Objects and Classes

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Methods

3:31 with Jason Seifer

Methods are extremely useful and powerful when writing classes. A method can manipulate the data inside of an instance of a class and return or format that data in new and interesting ways.

Code Samples

class Name
  attr_accessor :title, :first_name, :middle_name, :last_name

  def initialize(title, first_name, middle_name, last_name)
    @title = title
    @first_name = first_name
    @middle_name = middle_name
    @last_name = last_name
  end

  def full_name
    @first_name + " " + @middle_name + " " + @last_name
  end

  def full_name_with_title
    @title + " " + full_name()
  end


end

name = Name.new("Mr.", "Jason", "", "Seifer")
puts name.full_name_with_title

nick = Name.new("Mr.", "Nick", "", "Pettit")
puts nick.full_name_with_title

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    Classes are useful for more than just storing attributes for 0:00
    the abstraction that we're working with. 0:03
    We can write methods inside of our classes. 0:06
    Writing methods inside of classes is powerful, because the methods can 0:10
    apply only to the individual instance that we're working with. 0:14
    Let's go ahead and take our Name class and add a method to it now using Workspaces. 0:19
    So, we've got our Name class and I just changed this to be an attr_accessor for 0:25
    a title, first name, middle and last name. 0:30
    So, we know that we're going to have all of those different methods set for us. 0:32
    Now, we can create our own methods to work with in classes. 0:37
    So, let's go ahead and create a method called full_name. 0:42
    [SOUND] And what this is going to do, 0:47
    is return the first_name, 0:54
    middle_name and last_name. 0:59
    And we'll put a space in between there too. 1:04
    [BLANK_AUDIO] 1:06
    Now instead of all of this different stuff right here we can call name.full_name. 1:16
    Let's go ahead and run that and see what happens. 1:23
    Okay. 1:28
    This prints out. 1:29
    Pretty much what we wanted. 1:30
    But let's put a space here. 1:32
    Okay. 1:33
    [BLANK_AUDIO] 1:34
    That looks good. 1:38
    There we go. 1:41
    The correct thing has been printed out. 1:42
    Now we can also define another method. 1:46
    We'll say full_name_with_title. 1:49
    [BLANK_AUDIO] 1:50
    And in this one we will return the title and the space and 1:56
    we can actually just call this method because it returns a string. 2:01
    This uses something called an implicit return. 2:08
    Which means that the last item on the line is going to be the return value for 2:11
    the method. 2:16
    In this case, it's a string. 2:17
    So we can use the results of that string later. 2:20
    And it would be just like calling the method. 2:25
    So now, we could write full_name_with_title. 2:28
    And if we run this again, we get exactly what we were expecting. 2:35
    Now the nice thing about using classes and 2:40
    objects [NOISE] is that the variables only 2:46
    apply to that specific instance. 2:52
    So if we created, let's say we call this one nick, 2:57
    this variable would only have access to its internal variables. 3:04
    They are local to this variable. 3:13
    So if we run that again, we can see that that gets printed out just like we expect, 3:17
    and this allows us to abstract that logic away. 3:22
    And these are both fully contained and have access only to their respective data. 3:25

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