Actually None is much better for “magic” values: class Cheese(): def __init__(self, num_holes = None): if num_holes is None: … Now if you want complete freedom of adding more parameters: class Cheese(): def __init__(self, *args, **kwargs): #args — tuple of anonymous arguments #kwargs — dictionary of named arguments self.num_holes = kwargs.get(‘num_holes’,random_holes()) To better explain the … Read more
From New-style and classic classes: Up to Python 2.1, old-style classes were the only flavour available to the user. The concept of (old-style) class is unrelated to the concept of type: if x is an instance of an old-style class, then x.__class__ designates the class of x, but type(x) is always <type ‘instance’>. This reflects … Read more
The differences between a class and a struct in C++ is: struct members and base classes/structs are public by default. class members and base classes/struts are private by default. Both classes and structs can have a mixture of public, protected and private members, can use inheritance and can have member functions. I would recommend you: … Read more
The reason you need to use self. is because Python does not use the @ syntax to refer to instance attributes. Python decided to do methods in a way that makes the instance to which the method belongs be passed automatically, but not received automatically: the first parameter of methods is the instance the method … Read more
Is there any reason for a class declaration to inherit from object? In Python 3, apart from compatibility between Python 2 and 3, no reason. In Python 2, many reasons. Python 2.x story: In Python 2.x (from 2.2 onwards) there’s two styles of classes depending on the presence or absence of object as a base-class: … Read more
The java <class-name> command syntax First of all, you need to understand the correct way to launch a program using the java (or javaw) command. The normal syntax1 is this: java [ <options> ] <class-name> [<arg> …] where <option> is a command line option (starting with a “-” character), <class-name> is a fully qualified Java … Read more
Short Answer Use $this to refer to the current object. Use self to refer to the current class. In other words, use $this->member for non-static members, use self::$member for static members. Full Answer Here is an example of correct usage of $this and self for non-static and static member variables: <?php class X { private … Read more
Variables declared inside the class definition, but not inside a method are class or static variables: >>> class MyClass: … i = 3 … >>> MyClass.i 3 As @millerdev points out, this creates a class-level i variable, but this is distinct from any instance-level i variable, so you could have >>> m = MyClass() >>> … Read more
super() lets you avoid referring to the base class explicitly, which can be nice. But the main advantage comes with multiple inheritance, where all sorts of fun stuff can happen. See the standard docs on super if you haven’t already. Note that the syntax changed in Python 3.0: you can just say super().__init__() instead of … Read more