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We're going to be creating a class that will approximate a bank account. In this first video, we'll lay the groundwork for our program and define the class and an internal variable.
Code Samples
class BankAccount
def initialize(name)
@name = name
@transactions = []
end
end
bank_account = BankAccount.new("Jason")
puts bank_account.inspect
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[MUSIC]
0:00
So far we've learned about how to write
classes and methods.
0:04
We've also learned about the different
kinds of variables we can use in
0:09
our classes.
0:12
Let's put it all together and write the
simple bank account class.
0:14
We're going to be using all of the classes
we've learned about so far.
0:18
String, numbers, arrays and more.
0:22
We'll be doing all of this inside
workspaces, so let's get to it.
0:25
Okay, so let's go ahead and create our
bank account class.
0:30
So, let's go to the File > New File.
0:36
We're going to call this bank_account.rb.
0:41
Conventionally, we use all lowercase
letters and
0:48
where there would be a space, we put an
underscore.
0:52
So now, let's write our bank account
class.
0:56
We start out by defining a class using the
class keyword.
1:00
And then, we type the name of the class
that we want.
1:05
In this case, it's BankAccount.
1:08
[BLANK_AUDIO]
1:10
When naming classes, we have to
1:12
have a capital letter as the first part of
the class name.
1:16
And then, if we have more than one word in
the class name,
1:23
like we do with BankAccount, we make that
second word have a capital letter as well.
1:26
This isn't strictly necessary, but
1:32
it is how a lot of Ruby programmers write
Ruby code.
1:35
So it's important to follow these
conventions.
1:39
Now, let's go ahead and define the
initialize method,
1:43
which gets called when we instantiate our
class.
1:47
Now let's think a little bit about what we
need inside of a bank account.
1:51
We need to know who the account belongs
to.
1:56
So, let's go ahead and have a name
attribute in our bank account.
1:59
And we'll send that in when we create the
account.
2:05
[SOUND] Now, our bank account is
2:08
also going to have transactions.
2:13
The transactions are going to be all of
the debits and
2:18
credits that occur on the account.
2:23
We can use an array to take care of
holding that information.
2:26
Therefore, when we start this bank
account,
2:31
let's go ahead and create an empty array
of transactions.
2:34
Now let's go ahead and initialize our bank
account and see what it looks like.
2:41
[SOUND] And let's go ahead and
2:45
print out the bank account instance now.
2:50
And run inspect on it just to see what it
looks like.
2:57
[SOUND] Okay, we can see we have a new
BankAccount class,
3:00
has a name, and an empty array of
transactions.
3:07
So what we've done here, is we instantiate
a new instance of
3:13
the BankAccount class and assign it
to this bank_account variable.
3:19
When we define this method,
3:25
the initialize method, this gets called
when we instantiate the instance.
3:27
So calling new will instantiate an
instance of the bank account and
3:34
run this method.
3:39
We defined an argument called name here
which we set to an instance variable.
3:41
Therefore, we have to send in a name when
we
3:48
instantiate the new instance of the bank
account.
3:52
We then have an empty array of
transactions which we will begin to
3:55
fill out in the next video.
3:59
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