This is very important to understand.

Key Takeaways

context managers and I'm going to show you the very classic example but it's an important concept to understand. Now let's say we're working with a file in Python and we have something like this and believe it or not this can happen. What we can do is we can open a file using this open function and then we can write the file. However, if you use this approach you need to explicitly close the file. That's because if you don't close the file then it's still going to be held in memory and you can potentially have some memory leaks. So what would happen if an exception occurs before the file can be explicitly closed? Well, if that's the case, then we would have some kind of resource leak because we never closed the file and we're still storing that file handle. So I'm going to show you an approach that fixes this problem called context managers. I know this is a little bit of a trivial example, but the point is to demonstrate what a context manager is. So again, just keep in mind in this situation, I open a file, I write to the file, and then I need to close the file manually. And if something goes wrong before I'm able to execute this line, then that is potentially troublesome. Now the context manager handles this for us. We can say with open as f. Now what happens is this context manager manages the context of this resource and automatically cleans it up as soon as we exit the context manager. Context manager as it kind of describes is handling what happens with a particular resource. And you'll see this very commonly if you're using things like databases or opening again files. So we open this file and then what happens is in the background based on how this is written, it will automatically perform any cleanup operations for us as soon as we exit this indented block. What that means is that even if we have an exception within this width block here or anywhere else in our program, it will automatically handle closing the file for us. So we don't need to worry about it. And it's just really the best practice.