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[MUSIC]

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So far we've learned about how to write
classes and methods.

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We've also learned about the different
kinds of variables we can use in

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our classes.

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Let's put it all together and write the
simple bank account class.

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We're going to be using all of the classes
we've learned about so far.

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String, numbers, arrays and more.

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We'll be doing all of this inside
workspaces, so let's get to it.

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Okay, so let's go ahead and create our
bank account class.

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So, let's go to the File > New File.

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We're going to call this bank_account.rb.

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Conventionally, we use all lowercase
letters and

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where there would be a space, we put an
underscore.

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So now, let's write our bank account
class.

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We start out by defining a class using the
class keyword.

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And then, we type the name of the class
that we want.

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In this case, it's BankAccount.

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[BLANK_AUDIO]

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When naming classes, we have to

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have a capital letter as the first part of
the class name.

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And then, if we have more than one word in
the class name,

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like we do with BankAccount, we make that
second word have a capital letter as well.

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This isn't strictly necessary, but

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it is how a lot of Ruby programmers write
Ruby code.

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So it's important to follow these
conventions.

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Now, let's go ahead and define the
initialize method,

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which gets called when we instantiate our
class.

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Now let's think a little bit about what we
need inside of a bank account.

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We need to know who the account belongs
to.

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So, let's go ahead and have a name
attribute in our bank account.

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And we'll send that in when we create the
account.

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[SOUND] Now, our bank account is

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also going to have transactions.

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The transactions are going to be all of
the debits and

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credits that occur on the account.

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We can use an array to take care of
holding that information.

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Therefore, when we start this bank
account,

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let's go ahead and create an empty array
of transactions.

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Now let's go ahead and initialize our bank
account and see what it looks like.

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[SOUND] And let's go ahead and

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print out the bank account instance now.

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And run inspect on it just to see what it
looks like.

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[SOUND] Okay, we can see we have a new
BankAccount class,

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has a name, and an empty array of
transactions.

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So what we've done here, is we instantiate
a new instance of

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the BankAccount class and assign it 
to this bank_account variable.

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When we define this method,

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the initialize method, this gets called
when we instantiate the instance.

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So calling new will instantiate an
instance of the bank account and

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run this method.

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We defined an argument called name here
which we set to an instance variable.

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Therefore, we have to send in a name when
we

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instantiate the new instance of the bank
account.

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We then have an empty array of
transactions which we will begin to

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fill out in the next video.