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Closures

2:36 with andi mitre

In Scala you can define a function inside another function or method and then access any variables in the enclosing scope. In this video we’ll learn about closures and how to implement them.

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New Terms:

Closures -- A closure is a function whose return value depends upon a variable declared outside the function scope

Further Reading:

Examples of closures
Scala style Next steps with Scala

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A closure is a function whose return value depends upon a variable 0:00

declared out the function scope. 0:04

Basically with closures, means a variable and 0:07

a function where the variable is no longer in scope. 0:10

Let's dive in and create a closure. 0:13

Let's create a function called a reverse it which will take a string argument 0:16

consisting of our superhero name and a prefix. 0:20

Then it will concatenate the two and reverse the result. 0:23

Let's dive back into the code editor and clean up some of our earlier code. 0:27

So far, we've created a prefix variable which is not a vowel because we'll need to 0:56

change this later in the reverse hit function. 1:01

Let's see how we can use these two, to really show how powerful closures can be. 1:05

In this case, we call the function reverse it by passing the value Thor. 1:17

Let's also check out another example. 1:22

Let's change prefix to "Super Fast." 1:25

In the second example, we call reverseIt, passing it "Wonder Woman." And 1:41

also we've changed the prefix to super fast. 1:45

But what happens when we print out Thor and or when we print out Wonder Woman? 1:49

Let's compile and check out the results. 1:59

Although it's a bit difficult to read, 2:04

we notice that that first prefix is set to lightning. 2:06

And the reverse it function uses the variable prefix which is not in scope. 2:10

We update the variable prefix to super fast. 2:15

However, calling Thor retains the correct instance of prefix. 2:18

I hope you enjoyed exploring Scala with me. 2:23

We've gone through quite a few concepts through out the stages. 2:26

And learned quite a bit about Scala. 2:29

Checkout the teachers notes for more resources and how to proceed from here. 2:31

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