Class BankAccount example

It's interesting that the coding camp that I am planning to attend to sent me some courses to read before it starts.

Congrats on attending Code camp. Which one are you going to? Just my curiosity.

Now I got several people saying that the some courses that I have been watching is gonna retired.

Yeah, the software development world is evolving fast, it's nice that here at Treehouse, new materials are constantly being produced to keep things up-to-date with the development landscape; and I'd suggest you give feedback to your Code Camp staffs to make sure the resource handouts they're handing over to students are updated as well.

In the other words, outdated?

Ummm ... I can't say it's outdated, the Ruby Foundations course was recorded using Ruby Version 1.9.x, though I'd say 95% of the course materials are applicable to the current version of Ruby; however, since Treehouse has produced a series of Ruby courses as replacement for Ruby Foundation using version 2.x, and it make use of Treehouse's new Workspace as coding platform, it's better that you learn from the new courses.

What's following after the bank_account = BankAccount.new("") bank_account.class # => BankAccount

This line

bank_account.class # => BankAccount

the .class is a method, much like deposit and show_balance defined in the BankAccount class definition; they are all methods.

What .class does is to tell you what class the bank_account object belongs to; it returns BankAccount, make sense, right?

You may say, wait a minute. My BankAccount class had deposit and show_balance methods defined, but I have never defined a class method, where does it comes from? It's a predefined method in Ruby, and since Ruby is the purest Object Oriented language, everything in Ruby is an object, you can try using the .class method call on pretty much anything.

[1,2,3].class    #=> Array
"abc".class     #=> String
3.class          #=> Fixnum

Do not confuse the .class with the class keyword.

class BankAccount  # class here is a keyword
  # detail omitted
end

When you use class by itself, it's a keyword, it triggers the class definition; whereas in bank_account.class, the .class is a method call. They are 2 totally different things. The key thing to take note here is that, whenever you see something in the form of object.xxx, that's the dot notation, it's used for calling a method on an object.

Hi William,

Thanks for the detailed reply. Will try to absorb with time. The camp that I am thinking about joining is located closer to where I live. It's local in a sense. Here is the web: https://www.alphacamp.co/sg/ Thought it's link is sg but I am in Taipei, Taiwan. : )

Often I have to read it several times. I wonder if it's the path that every developer experiences before. : )

Yes, it's totally normal, it can be quite intimidating at first.

class BankAccount  
  def initialize(name)
    @transactions = []
    @balance = 0
  end

  def deposit
    print "How much would you like to deposit? "
    amount = get.chomp
    @balance += amount.to_f
    puts "$#{amount} deposited."
  end

  def show_balance
    puts "Your balance is #{@balance}."
  end  
end

bank_account = BankAccount.new("Jason Seifer")

Also, on my first paragraph, I don't quite understand the bank_account = BankAccount.new("") and the rest. I mean after I write the class BankAccount, how will I know by using the bank_account 'format' the and rest to create things and make it function?

Okay, you have trouble understanding this line bank_account = BankAccount.new("Jason Seifer")?

You've previously defined a BankAccount class here.

class BankAccount
  # detail omitted
end

Here's a key point to understand -- class definition by itself isn't doing anything interesting, it only serves as blueprint (or specification) for constructing new BankAccount object.

To put it in plain English, think of class definition in OOP as cookie cutter, and object as cookie. Cookie cutter defines the shapes and size of the cookie, it's a tool you use to cut out cookies from dough.

That's exactly what this line does bank_account = BankAccount.new("Jason Seifer").

• In Ruby, .new() is how you create a new object based on class definition
• BankAccount.new("XXXXX") creates a new BankAccount object based on the class definition of BankAccount, and then assign it to the variable bank_account; it takes one argument -- "XXXXX", why? because in the class definition body, the def initialize(name) requires a name argument.

I hope that I am able to help you understand these OOP concepts a little bit.

Right now you're at a pretty early stage of learning Ruby OOP, it's okay that you don't get all these terminology and concepts at the first try, it's online course that you can re-watch as many times as needed; but it's important that you go on with the course and learn more about OOP thinking, because they help you see the bigger picture.

One last thing, this Ruby Foundation course is very much retired. You should switch to a more updated version of this course.

• http://teamtreehouse.com/library/ruby-objects-and-classes
• http://teamtreehouse.com/library/build-an-address-book-in-ruby

Thanks William! Your explanation does help me a lot. I will watch the two videos.

It's interesting that the coding camp that I am planning to attend to sent me some courses to read before it starts. Now I got several people saying that the some courses that I have been watching is gonna retired. In the other words, outdated? How will I know if the camp is really helping me out? (off the track I know sorry. You don't need to answer this.) : P

I have one more question. What's following after the bank_account = BankAccount.new("") bank_account.class # => BankAccount or in the extra credit part, the example of your_name.name_length, that is the logic flow to become this way?

Thank you very much for these!

Ann

Thanks a lot William, all of these was really helpful also for me!