Python Abstract Property Example

Python comes with a module which provides the base for defining abstract base classesabc and that module name is abc. Yet python comes with a module which provides the infrastructure for defining abstract base classes abcs. From abc import abc abstractmethod class myabstractclassabc.
python abstract property example

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Python abstract property example. Python programming provides us with a built in atproperty decorator which makes usage of getter and setters much easier in object oriented programming. Python runtime services next. By default python does not provide abstract classes. The following are code examples for showing how to use abcabstractpropertythey are from open source python projects.

Atproperty atabstractmethod def mypropertyself. Table of contents previous. These can of course be further derived. Atexit call functions when a program is closing down.

In the above example the abstract class is shape which contains one concrete method called common and two abstract methods called area and perimeter. This module provides the infrastructure for defining abstract base classes abcs in python as outlined in pep 3119. Abstract base classes provide a way to define interfaces when other techniques like hasattr would be clumsy or subtly wrong for example with magic methods. Abcs introduce virtual subclasses which are classes that dont inherit from a class but are still recognized by isinstance and issubclass functions.

Before going into details on what atproperty decorator is let us first build an intuition on why it would be needed in the first place. This module is called for obvious reasons abc. The collections module has some concrete classes that derive from abcs. In python 36 lets say i have an abstract class myabstractclass.

Pass and a class myinstantiatableclass inherit from it. In fact python on its own doesnt provide abstract classes. Abc works by decorating methods of the base class as abstract and then registering concrete classes as implementations of the abstract base. The output from all the example programs from pymotw has been generated with python 278 unless otherwise noted.

See the pep for why this was added to pythonsee also pep 3141 and the numbers module regarding a type hierarchy for numbers based on abcs. Our example implemented a case of simple inheritance which has nothing to do with an abstract class. There are two child classes square and rectangle that inherit the abstract class shape and implement the abstract method. So how do i write to the property myproperty on.