There are multiple system managers which can by possibly running on your Linux system. The current most common system managers are SysV (init), Systemd and Upstart. You may find this short guide to be of use to you, if you are unsure which, system manager is running on your Linux system.
Privileged access to your Linux system is required.
In some cases, it is necessary to disable Docker's IPtables rules to avoid overwriting any existing firewall rules. The following article describes a simple to follow procedure on how to disable disable Docker's IPtables rules on Systemd Linux systems.
Privileged access to your Systemd Linux is required.
Whenever you need some additional functionality in Python, you turn to the import keyword to pull in extras from Python modules. You've used common ones like the math module plenty of times.
Now, you will learn how to create your own Python modules and packages to compartmentalize your code. Modules are sort of like classes in that they make your code modular. While classes make code modular within a program and serve as the blueprints for objects, modules make all of your code modular across all programs and are utilities to be used just as they are.
Through the use of modules, you can create your own toolbox with all sorts of parts and pieces that you commonly use. Modules can include anything from variables and constants to functions and even classes. Because of this versatility, you can set yourself up to have everything that you need at the beginning of any project.
Polymorphism is yet another important aspect of Object Oriented Programming. No Warcraft fans, it doesn't have anything to do with turning people into sheep. That'd be much cooler. Instead, Polymorphism allows methods and functions to use classes with similar functionality in the same way.
Polymorphism cuts down on the amount of code that you need to write by eliminating redundancy in a logical and meaningful way. It relies on you, the programmer, to be clever in your design and harness similarities in objects.
What Is Polymorphism?
Polymorphism is one of those things that's hard to define in a single word or phrase. The term takes slightly different forms in different programming languages, making it a bit harder to pin down concisely. Generally speaking, and in Python, it's the ability of multiple different objects derived from different classes to be used in the same way.
To use the example of cars that this guide has been working with, imagine that you need to write a function that calls the move_forward method on any type of car that it's passed. Every object created from the original "Car" class or any of the subclasses that extend it should have a move_forward method, even if it's been overridden to do something slightly differently in some of the subclasses. This means that through polymorphism, you can write a single function that takes a "Car" object and calls move_forward. Since all of the objects instantiated from the subclasses of "Car" are still technically "Car" objects and have all of its original properties in some form or another, this will work.
Please note that the specification of a single superclass to use as an object type is not entirely necessary in Python. Python is not strongly typed, so you don't have to explicitly define which variable types a method or function takes. In languages like Java, this plays a role in how polymorphism behaves. However, in Python, it's a good idea to think of it along these lines to ensure that the objects that you pass will all have the method or property being used.