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Welcome back, everyone, to this lecture on modules and packages when creating complex code bases,

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we typically don't just use a single dot pie file instead.

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We would like to break up functionality across multiple python files and import our classes or functions

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as needed.

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Let's explore how to easily do this within Python.

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I'm going to jump back to our code editor.

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OK, so here I am inside a visual studio code, and I've expanded the explorer because I'm first going

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to start off by creating two new files one I'm going to call.

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My module, Dot Pi.

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And let's do two things inside my module.

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I'll define a function that let's say is super useful, like the use or, let's say, useful.

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Function and all this does is this kind of really silly function, just says print using the useful

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underscore funk.

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All right.

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So I have that available for me.

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It's a function within my module, that pie.

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I will also later on in this file, define a class.

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We'll call it useful class.

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And let's just say it has a very simple method.

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You just instantiate it, let's say in it, and you instantiate it with some message you want to relay

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later.

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So say salt, that message is equal to message, and then it's going to have a method called, let's

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say, report.

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Takes and self and report just prints out the message itself, says self that.

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Message.

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OK.

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So notice two things I have here, I have a function that is really useful to me and I want to use it.

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It's in my module that PI, as well as a class with a method I can call.

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So now we want to be able to use both this function and this class, as well as the methods associated

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with that class in another file.

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How do we do that?

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I'm going to create a new file and now let's call it my program Dot Pi.

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And so my program that PI wants to be able to use functionality from my module that PI notice right

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now that they're actually located within the same folder called Django Lectures.

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Later on, we're going to show you how to create essentially a package directory that you can then use

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that an import from other locations.

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But what I can do for right now, because they're located in the same directory that is, they're both

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located under Django lectures.

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I can say the following I can say from.

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My module.

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Import and then I can actually import the function useful function.

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So I say import useful func.

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And then here, later on in my code, I can actually then execute useful funk.

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So now look what I'm going to do down here at the terminal.

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I'm going to say.

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Python and I'm going to run my program, the PI, I hit enter and it says using the useful function.

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So now I understand that I can actually call functions here in my module, that pi from my program,

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that pi.

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Note that when you start doing imports, you may actually see Python automatically cash some of this

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functionality that way when you run this again in the future.

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It should, technically speaking, run faster for our level of understanding of Python, though it can

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kind of just ignore it.

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Don't delete it, but just go ahead and let it live there.

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Now we can also use classes, so instead of importing use func, what I could also do is say from my

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module.

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Imports and I can import the useful class, and the way this would work is I create my instance of a

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class so I can say my instance.

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Is equal to an instance, a useful class.

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Remember, it needs a message to be defined, so I'll just have this be.

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Hello.

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And then I'm going to say my instance and then I have a excu report.

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Save those changes.

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Run that and then it says hello.

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So that's how you can actually go from a file that's located in the same directory, like my module,

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that pie and then say from my module that is the name of that pie file import.

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And you can either import functions or classes or both.

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If you want to do multiple imports, you could do something like this comma and then say useful func

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and also use that.

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So then I could over here actually execute useful func and you can see that works pretty much the exact

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same way.

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Hello.

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And then using that useful func.

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Now let's imagine I have another folder.

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How would I actually use that?

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Well, what I can do is I'm going to create a new folder and we're going to call it my.

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Package note that I'm creating another folder, I'm not actually creating another Python file yet wanting

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to do in order to use my package.

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And let Python know that this directory name, which is technically not a Python file, can also be

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included as part of the pathway, is two things inside of my package.

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I need to create an empty file called Underscore Underscore.

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I end it underscore underscore that PI.

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This is going to let Python know that it's OK to use this folder name as part of its directory structure.

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When you're importing a file, it's actually labeling everything inside this folder as part of a package.

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And now let's actually create a new file here that will be called, let's say, my sub module Dot Pi

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and inside my sub module that PI, I will go ahead and create another kind of silly function here.

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So we'll say.

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My sub funk and all this does is it prints out using a function from.

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My sub module, that pie.

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OK, so notice the directory structure here, I have my package in order for Python to understand that

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this is now a package director I can use, I now have in it and then my sub module, so I come back

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to my program.

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And then what I can do because it hasn't in at that pie.

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I can now say from my package, dot my sub module, import some functionality from that particular file.

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So I come here and now that name is my sub func.

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So I come here and say, Import my sub func.

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So notice the syntax here.

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I now say from that director name dot the the actual Python file name import.

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Then the class and the function.

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Previously, we just did from the module.

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Import this now because I have this in it, that pie file.

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That's to underscore.

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Remember that I can begin to use the directory names themselves.

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So here then I can call my sub function.

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Have it run an execute.

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I'm going to run Python, my program, the pie again.

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And now it says, here, hey, I'm using a function for my sub module.

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That pie?

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OK.

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And that's the very basics of what we need to know for modules, imports and packages.

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There's technically a lot more that goes into it than what you've seen here.

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But just to get us started with Django, this is more than enough later on as we do various other types

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of imports.

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We'll let you know as we're doing them the specific context and syntax for that.

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But this is what you need to know so far.

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If the two Python files are in the same directory, you can easily just import them by saying from the

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module that pie import whatever classes or functions you're looking for.

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If you want them organized, then their directory, which you can begin to do, is simply open up that

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folder.

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Add in in in it that pie that is empty and then add in the modules like myself module and then say from

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that directory that and then the module.

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So that's a difference in a package and a module.

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The package is that actual directory, which should then include different types of modules, was themselves

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are just Python files.

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OK, that's it.

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I'll see in the next lecture.