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