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Now let's talk about the most important rule there is about clinical functions.

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It's to keep them fought, to keep them little.

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Smaller functions are the key for clinical, for mental ability, for scalability, for everything.

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There is a little quote I want to say to you that the first rule of function is that they should be

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small.

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The signal of function is that there should be more than that.

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So it really influences the fact that they need to be smaller and for them to be small.

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There is several stuff that we can do.

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The first one is that we have to ensure that they are doing one thing.

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For example, this little code right there, it's the function log in as first it login in the database.

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For example, we have a database like Superhighways or something else.

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Any give us an access token and then we save this access token and then we redirect the user and we

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notify.

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It's notified that it's a success.

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He's login.

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So what is wrong with this thing is that this function don't do one thing.

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It will tell me yes it does free.

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It's no more or we cannot but just one line in the function.

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That's not what I mean.

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I mean, that's there need to be one thing in the in their name with the goal of their name here.

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The goal is to log in.

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So it's log indexes.

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But getting saving ducks is looking to keep the decision of the user so it's normal and then it should

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be direct and notifier.

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This thing is not part of the log in goal.

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The logging goal is not to redirect the user to look and go in just to log in.

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The user eats an extra.

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It should not be there.

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It means that the function do log in and redirect a redirect.

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And this is not the name of our function.

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The name of the function is just a logging, not a logging and a redirect.

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So this path here will not be in this function.

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It will be in a purpose up in the function submit form, for example, but not in this scope.

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So this thing, we did it because it's not it should not be there basically.

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And here we have a function that does one thing and it's great because it's small shirt and it will

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be more easily to change refactor and to use it because when we use it, we will not have to always

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redirect the user.

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So it's way better that way.

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The second way to make a function smaller is by trying to extract another function from it.

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So for example, here I will uncomment this little code right there.

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Then we have a function submit log in.

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Yeah, it's well done.

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And this function is using the log in that we use and then is using the redirect to in the defined user

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that we put in the purpose as I told you.

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So this is where we put the thing, it was inside here we remove from log in and we put them in the

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purpose group.

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So it was the function submit logging.

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So in this function we will try to extract another function and we will see if we can, how we can know

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if we can extract or not.

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So it is by taking a group of line, a group of instructions, and by trying to find a name for them,

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a name for a function for them.

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So for example here my first step is to submit log in is to a checking the validity of the field.

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So this type of line here, can I put this group of in function and if I put them in the function,

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what will be the name of this function I can find?

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I can start to think I'm trying to validate some stuff.

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So it will be validate log into fields for example.

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And at this moment precisely you stop everything and you do it because you find a name that is proper,

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validate logging fields and it will work basically.

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So you just do it at function, validate, validate, log in fields up in barometer, username and password,

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and you just copy the code that you have.

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And now this function validate log in fields, you put it right there up and putting user and password

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in parameters and know your function submit.

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Logging A has become more little.

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It's become more effort shorter so it's way better that way.

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And we can see that we check the validity of the routine fields, we do the log in, we reject and we

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notify user.

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And if it don't work, then we notify the user that there was an error of course.

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So here the function is already you can see really more easy to read.

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It is really easy because it's basically text.

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It's text that you read and it's way better that way.

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And another way of saying this extraction as a function, it's bypassing the level of abstraction extraction

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levels.

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What is an extraction abstraction level?

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It's kind of a hidden, hidden wall or stuff like this that we put on the code to not see the details

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of an implementation.

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So here, for example, in the function submit login, I need to know.

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That doesn't mean looking to do the meditation.

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Yes.

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But do I need to know how this validation is done?

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Not for sure.

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When I'm in the I don't need to always to know how validation is done.

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So it's okay if the radiation is hidden in another in another function.

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It's okay to put this level of abstraction in the validation, because the setting login is not only

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about this, it's about several steps.

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So I need to know the steps, but I don't need for the implementation of those steps.

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So this is the limit of abstraction.

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And by doing that, by doing a lot of assumptions, you will be able to have shorter function.

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So this is really an important concept to remember, too.

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So to keep the function short, do only one thing and extract a function to create a level of abstraction.