Lesson 15 Classes

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Transcript

Classes and objects, surprising at first, there are no private or protected quantifiers everything is public. By convention, a variable is for internal use, it is named with an underscore in front, no destructor or destructive need. A special methods are framed by two underscores, for example, def double underscore in it, double underscore of self, colon, enter pass. A variable whose name begins with two underscores is inaccessible directly raises an exception attribute error, except that there's always a way to access it in Python. Some attributes of the classes, there's no abstract class notion there are multiple inheritance to c++ depth, first lecture, right. The methods are all Virtual class has attributes.

It has special methods. Function super will refer to the parent class. To declare it, you write the class name, colon, enter, and below that you write instructions. Here's an example. We declare the class time that has the init method. It has three attributes, hours, minutes, and seconds.

The class has to show our method that prints the time and the time format. This can be given by the user or can be taken from the system. In it, the initializer requires constructor double underscore in it, double underscore, the day classical function, you can define parameters default are not named or not. methods in Python, there's no private attribute. Everything is public. This means that if you want to modify an attribute from outside the class, you can just like the show our method.

Here we define the Translate method object. A class attribute is an attribute that belongs not to the object, but to the class. A class underscore attribute is accessible from a class without creating an instance. So without having to do a class. On the other hand, object underscore detail is not accessible if there is no instance. An instance has access to both class and object attributes.

We use here a decorator, who says that the method is a class method, therefore accessible without creating any instance. The class method notation transforms the method to a class method. The naming convention changes. The first argument is no longer called self, but CLS. Let's try to make private counter replaced counter by double underscore counter, it does not work, you can no longer directly access type of self dot double underscore counter. So you need a method that returns the double underscore counter.

Accessing a class attribute from an instance method works. But if you call robot robot instances, it gives an error. It takes an instance to know the value of the counter is not good. If one removes itself, the method becomes inaccessible from the object. On the top left example, robot instances is accessible from class to class. Thanks to the Add static method, robot instances decorator is accessible from the class and the objects on the lower left example.

Static methods versus classes methods. A static method is a method that knows nothing about the class or instance that invokes it just Get the arguments that were passed. No first argument implicit itself or CLS. It is almost useless in Python. You can use the module function that a class method is a method that receives the class, then invokes it as the first argument. It is useful when you want the method to work with the class, or these base classes.

Here, the class method called the static method, special methods and attributes. The name of a special method takes the form, double underscore special method double underscore. Special attributes double underscore dict double underscore. By default, when you develop a class object, both from this class will have a special double underscore dict double underscore attribute. This attribute is a dictionary that contains as keys, the names of the attributes and as values, the values of the attributes For example, object dot double underscore dir double underscore gets the attribute dictionary, special methods and attributes. Method double underscore del double underscore, which will be called at the time of destruction of the object.

Double underscore r EPR double underscore method affects how the object is displayed when you type the name directly. special method double underscore str double underscore, especially uses to display the object with print. By default, if no double underscore str double underscore method is defined. Python called the double underscore or EPR double underscore method of the object. The double underscore str double underscore method is also called if you want to convert your object to a string with the constructor str. A special method double underscore get a TT er Double underscore allows to define a method of access to our attributes.

This method is called when you type object dot attribute, not to modify the attribute, but simply to access it. Python searches for the attribute and if it does not find it in the object, and if they double underscore get a T tr double underscore and method exists, it will call it by passing the name of the attribute in question as a parameter in the form of a string of characters. The double underscore set at tr double underscore method defines access to an attribute for editing. If you right object dot attribute underscore name is equal to new underscore value. This special method double underscore that at our double underscore will be called object dot double underscore set at tr double underscore Core, attribute underscore name, new underscore value. Again, the name of the searched attribute as passed as a string.

This method is used to trigger an action as soon as an attribute is modified. The double underscore del att or double underscore method is called when you want to remove an attribute from the object doing the object dot attribute. In addition to self, it takes the name of the attribute to be deleted. mathematical operators overload the special methods allowing the overload of mathematical operators double underscore ad double underscore overload operator plus double underscore sub double underscore operator overload minus double underscore mall double underscore operator overload star Double underscore true di v double underscore, operator overload, dash, double underscore floor diff, double underscore, operator overload, double dash, integer division, double underscore, mod double underscore, operator overload, percentage sign, modulo double underscore call double underscore, operator overload, double star power. It is also possible to overload the operators, plus equals, negative equals and etc. The function this function allows you to combine several lists into one in order to make the iteration more efficient.

Does perform the following function for a list ABC and another list D, E f. That will give us a list a comedy at the top And b comma e as a tupple. Local function, it is possible to define a local function, including it and another function, as you can see in these examples. This is all for this part of the course. Thank you for taking part in it. Hope to hear from you

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