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Ruby Gems

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Gem Usage

3:04 with Jason Seifer

Now that a gem is installed, we need to know how to use it.

Now that we know what gem we want to use and 0:00
have it installed, we have to be able to use it in our program. 0:03
Let's see how that works now using work spaces. 0:07
So now that we have the money gem installed, let's go ahead and 0:11
see how to use it in one of our programs. 0:14
First, I'm actually going to scroll down the right side of the screen 0:17
on the ruby gem documentation page, and 0:20
I'm going to click the documentation link, and then we'll see what it gives us. 0:23
Right now, I'm going to click on the API documentation, and 0:32
then, let's see how to use it in one of our programs. 0:37
Well, we've done the gem install, so let's go ahead and see how to use it. 0:40
In this example, there's $10 US. 0:46
Now first, we'll need to require the gem, 0:49
so let's go back to our work space and create a new file. 0:51
We're going to call this money_example.rb. 0:58
Now once a gem is installed, the first thing that we need to do is require it. 1:05
So, we’ll require money. 1:10
If only it were that easy in life. 1:14
Now that it’s required we can use it, so I’m going to go back and 1:17
consult the documentation. 1:20
It looks like we can initialize a new money instance by calling the class name 1:23
money, and the word new, and then give it the number of cents in a currency. 1:27
Let's go ahead and try that. 1:33
And, for right now, let's just print that to the screen. 1:42
Now, I'm gonna click down into the console, and run this program, 1:49
and it gives us a money instance. 1:55
So, at this point, we've installed a gem, and used it in a very simple program. 2:00
Let's go ahead and create another one, more_money. 2:07
And let's print this to the screen as well. 2:22
Run this one more time, and 2:26
we can see that we have successfully added two units of money together. 2:29
And that's really all that's required to use a gem once we've got it installed. 2:35
Just use the require statement. 2:40
Ruby will then find the gem and import it for you in to your program. 2:43
Generally, the require statement is going to be the same name as the gem. 2:49
In this example it was called money. 2:54
If we had installed another gem, such as multi jason, 2:57
we would require multi jason instead. 3:00