Can a class have no instance variables?
Class methods cannot access instance variables or instance methods directly—they must use an object reference. Also, class methods cannot use the this keyword as there is no instance for this to refer to.
Should instance variables be public?
The instance variables are visible for all methods, constructors, and block in the class. Normally, it is recommended to make these variables private (access level). However, visibility for subclasses can be given for these variables with the use of access modifiers. Instance variables have default values.
How to create an instance of a class in Python?
We can create an instance of the Shark class (we’ll call it new_shark) and print the variable by using dot notation: Our program returns the value of the variable. Just like with any other variable, class variables can consist of any data type available to us in Python.
How are class variables defined in Python 3?
Class Variables Class variables are defined within the class construction. Because they are owned by the class itself, class variables are shared by all instances of the class. They therefore will generally have the same value for every instance unless you are using the class variable to initialize a variable.
How to initialize instance variables in Python constructor?
To initialize instance variables within the constructor, is – as you already pointed out – only recommended in python. First of all, defining all instance variables within the constructor is a good way to document a class. Everybody, seeing the code, knows what kind of internal state an instance has.
Is it really correct to declare all instance attributes in Python?
Yes, you should assign all attributes of your object in the __init__ method. The most important reason to do this is tool support. Many Python IDEs can see the assignments in the __init__ and use those attributes for type-based autocompletion. Sphinx-doc can list those attributes in your reference documentation.