Python:Classes

Create your own classes

self

The namespace of the current instance. Can have any name, 'self' is commonly used.

__init__(self, <parameters that can be provided with default value>)

Constructor, automatically called when the object is instantiated. Use this to initialize the object attributes. An object is instantiated by just assigning a class to a variable. a = class(initial attributes)

__del__(self)

Destructor, automatically called when the object is removed.

__str__(self)

Returns the string representation of the object. E.g. if you use print(object) or str(object)

All interaction with the object should go via a method, not to variables in the class (use interface, not implementation). Python has no mechanism to enforce this. Variable name can be obfuscated by putting underscore before their name. You can do this with methods too that should not be called directly but only from other methods.

Example:

class Medium:
    def __init__(self, title='', price=0):
        self.__title = title
        self.__price = price
    
    def __str__(self):
        return "Title: {0}\nPrice: {1:6.2f}".format(self.__title,self.__price)

    def gettitle(self):
        return self.__title

    def settitle(self, title):
        self.__title = title

    def getprice(self):
        return self.__price

    def setprijs(self,price):
        self.__price = price

    def getall(self):
        return [self.gettitle(),self.getprice()]