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And this lecture we're going to start talking about utility traits.

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And utility traits are a grab bag of various traits from the standard library that have enough of an

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impact on the way rest is written, that it's important for us to be familiar with them.

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So the first one that we're going to look at is the drop tray.

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And we've heard the word drop being used kind of throughout this course.

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And when we talk about dropping and rust, we are referring to the freeing of the resources the value

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is using.

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Drops occur in a number of situations, such as when a variable goes out of scope at the end of an expression,

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removing elements from a vector and the list goes on and on.

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Luckily Rust almost always will handle this for us, but it is an important trait to know.

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So let's look at how we can use it.

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So we'll piggyback off of our struct course and what we'll do is we'll implement drop for course.

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And then we're going to have the drop function, which is going to contain a mutable reference to the

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self.

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And then in here, just to demonstrate how it works, we'll say we're dropping.

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And then we'll just say self dot art author.

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So now when we come down here, we can manually call this ourselves and we can say drop course one because

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that is what used our course.

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Struct and now if we run it, we'll see that it says dropping Tyler.

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So we manually call this drop trait and we manually freed up our resources, but we could delete this

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line.

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And rerun this and see that it still calls dropping.

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Tyler because here is where course one went out of scope and so it called our implementation of drop

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which.

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We told to hey print out dropping Tyler and then free up the resources so.

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That is what the drop trait is.

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And now let's go look at a couple more.

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Starting off with what the clone trade is.