Getting to Know the Example Function

00:00 Let’s take a look at a small example. Here I have a function, it’s just an example function that takes as an input, a file object, and then does something with that file object and returns some output, right?

00:13 In this case, what it does is it reads this file object and then just uppercases the text content that’s in there and therefore it’s aptly named as upcase_file_content().

00:24 So again, this is just an example and I also have an example text file here, and now I want to upcase these. So what you would do when you just normally open the file, you would use the open() function and then just run upcase_file_content().

00:39 Let’s try it out in the terminal.

00:42 I’m going to use the ptpython shell, but anything that I do in here works also if you want to use a different shell.

00:51 So first I will need to import this function into my REPL session.

00:55 I’m gonna type from process import upcase_file_content(), and it’s a good practice to open a file using a context manager. So I’m gonna use the with statement and say with open(), put in the file name.

01:10 This is example.txt. I’ll open it in read mode,

01:16 and I’ll call it f for short here. And now I want to call upcase_file_content() and pass it that file object, right? And let’s also print() the output so it looks the same.

01:31 Alright, so this is a way I would use this upcase_file_content() function. And you see it works. It takes the input from example.txt and then upcases it.

01:41 Alright. What I’m working with here is a function that takes as an input a file object. But now what if you want to simulate this file object, you don’t actually have that file.

01:53 And maybe you’re working in an environment where you can’t create that file, for example, for tests. We’re gonna look at that a little later as well. But for now, I want to show you the solution and how you can simulate such a file object like this example.txt, using Python and just Python standard library.

02:10 Let’s do that in the next lesson.