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Previously, we looked at simple Python decorator functions.

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And the reason why it's simple is because all that we're doing when we're

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calling the function in the decorator is we're just calling it straight up.

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But this doesn't take into account in the cases where, for example,

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we want to add a condition before we called the function or even more advanced.

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What if we needed to call the function with some sort of inputs?

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How would we get hold of that? If it was inside a decorator?

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So let's say that we had a class called user.

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Now, if you are not familiar with classes,

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I strongly recommend going back to the lessons where we covered classes and

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Object in great detail.

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We did over several days just to make sure that you're up to date with that

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before you continue. But this is a pretty simple class.

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All it does is it has two properties, a name, property,

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and it is logged in property.

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So basically what we're trying to simulate is a condition where let's say we had

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a blog website and we had these user objects and the user has a username and

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also some sort of property that keeps track of whether,

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or if the user is going onto the website and not logged in,

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or whether if they all have already logged in.

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So certain methods on the website,

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you can only be achieved by users who are logged in it's. For example,

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if they wanted you to create a new blog post we'll,

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then that user has to be checked.

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And we have to make sure that they are in fact logged in and authenticated to

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create a new blog post.

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If I go ahead and create a new user from the user class,

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then I can give it a name, which I'll put as Angela.

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And then I could create the blog post and pass in my user.

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Now, when I hit run, you'll see, this is Angela's new blog,

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post being printed right here.

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Now what if I wanted to create a decorator function that could be used to

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decorate any function on our website that requires authentication.

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So it requires that this users is logged in property is set to true.

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So let's say that I decided to create my decorator function right here,

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which I'll call the is authenticated decorator.

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And this is of course going to need to take a function as an input.

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And then inside, we've got our wrapper function.

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Now inside our wrapper function is where we call this function.

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That's the past and right here.

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And finally to complete our decorator.

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We have to return the wrapper as a function without the parentheses.

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Now, in order to check for the is authenticated,

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what we actually want to do is we want to say, well,

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if the user.is logged in is equal to true will in that case,

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we're going to trigger the function. But if it's actually not true, well,

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then we're not going to trigger the function. Now,

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the only problem here is that this user is undefined.

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We were only able to pass in the function,

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but what if we needed to pass in some arguments associated with that function?

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Notice here that all function create blog posts, which is what we want to add.

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The decorator to accepts an input in the form of the user. Object.

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If I decorate this function with the is authenticated decorator,

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and I tried to run this,

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then it's not really gonna work because that user is not defined.

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And it tells us that the wrapper function takes zero positional arguments,

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but one was given.

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And the one that's given is this user right here,

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this era might already be a good hint for us to figure out how to fix this.

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One of the things that we talked about in previous lessons is the concept of OGs

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and clogs, unlimited positional arguments.

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Normally all add it in as asterix,

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OGs and unlimited keyword arguments are usually added in as two Astrix and then

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Crocs. So now we can have all function,

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which is decorated with this decorate to function.

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And when we call the function,

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we could provide some inputs and those inputs can be tapped into via these OGs

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and Crocs. Now, in this case,

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this is a positional argument and it's the argument App positions zero.

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So instead of using this user, which is what we would do,

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if we were inside this function, instead,

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we would use the wrappers OGs,

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and then we would use the position set to zero.

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So now it's going to look at the function that is going to be passed in which is

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going to have some inputs.

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And it's going to take that first position input and then see if it is logged in

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property is equal to true.

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Now that my wrapper is taking positional arguments and keyword arguments,

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and I can tap into the first positional argument by using Oxy zero.

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Well inside the rapt function,

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I can now also use this first argument in order to give it as an input to that

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function.

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Remember that this function is simply this create blog post function without the

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decorator. Now, if I go ahead and hit run,

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you will see that nothing happens unless I change this users is logged in

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property to equal. True. And now that that's true,

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then it's going to be checked right here.

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And then it's going to call the function because that user is now logged in this

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idea of being able to pass in positional arguments,

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as well as keyword arguments,

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by simply adding the odds and quarks to the wrapper function,

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and then using it inside the wrapper or using it to call the function itself is

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one step higher in terms of understanding Python,

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decorator functions.

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I recommend spending a few minutes looking at this code,

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which you can access at this URL, which is in the course resources,

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and then trying to recreate this functionality from scratch based on your

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understanding of what we just talked about in the next lesson,

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I've got a coding exercise for you so that you can try out this new advanced

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form of Python decorators and try creating one yourself.