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We saw at the beginning of the lesson, what are the

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goals of refactoring? Or what are the reasons ,why we need to

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refactor in the first place? The first reason is that requirements

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change, and when the requirements change, we often need to change our

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design accordingly. In other cases if any of the requirements unchange,

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we might need to improve our design. And this happens for many

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reasons. For example, we need to add a new feature, we

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want to make the code more maintainable, and also in general programmers

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don't come up with the best design the first time. So they might

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need to adapt it after the fact. And the final reason I want to

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mention is sloppiness, and to some

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extent laziness, of programmers. And a typical

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example of this is something that we all have done, which is copy

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and paste programming. So instead of rewriting a new piece of code, because

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we know that there is some code in some other parts for the

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program that does a similar thing, we'll just copy the code over. And

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before we know, we end up with tons of copies of the same functionality.

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And when that happens, a good way of consolidating that code and

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extracting that functionality is to use refactoring, for example, by creating a

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method or a class that provides the functionality. And we'll see specific

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examples of that. A question I would like to ask at this

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point of the class is whether you have used refactoring before? So

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I want you to take a second and think about it. And

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no matter what you're history is, if you ever coded I bet

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you any money that the answer is yes, you have done refactoring.

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What do I mean? I'm going to give you an

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example. I'm sure you renamed the class or a

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method or change the name of some variables in

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the code before. That's refactoring. Even something as simple as

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renaming a class is refactoring, because, for example, it

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might help you making your code more understandable. And of

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course I'll admit that in this case, this is

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a trivial refactoring, and there are much more interesting ones.