Why use abstract base classes:
Abstract classes allow you to provide default functionality for subclasses. Compared to interfaces, abstract classes can have an implementation. By defining an abstract base class, you can define a common application programming interface (API) for a set of subclasses. This feature is especially useful in situations where third-party developers provide implementation, for example using plugins in your application, but can also help you when working in a large team or with a large codebase where all the classes are stored in your application. The head is difficult or impossible.
How abstract base classes work:
In python, by default, it cannot provide abstract classes, but python offers a module that provides a base to define abstract base classes (ABC), and this module is called
ABC . ABC works by marking base class methods as abstract and then registering concrete classes as implementations of the abstract base. A method becomes abstract if it is decorated with the
@abstractmethod keyword. For example —
I have 3 sides I have 4 sides I have 5 sides I have 6 sides
I can walk and run I can crawl I can bark I can roar
Implementation via subclasses:
Subclasses directly from the base avoid the explicit registration of the class. In this case, Python class control is used to recognize
PluginImplementation as an implementation of the abstract
A side effect of using direct subclassing is that you can find all implementations of your plugin by asking the base class for a list of known classes derived from it.
Concrete methods in abstract base classes:
Concrete classes contain only concrete ( normal) methods, whereas an abstract class contains both concrete methods and abstract methods. A concrete class provides an implementation for abstract methods, an abstract base class can also provide an implementation by calling methods via
super () .
Let's see an example to call a method using super ():
Abstract Base Class sub class
In the above program, we can call methods in abstract classes using
super () .
Abstract classes include attributes in addition to methods, you can require attributes in concrete classes by setting them with @abstractproperty.
# Display Python program
# abstract properties
Exception as err:
Can't instantiate abstract class parent with abstract methods geeks child class
In the above example, the base class cannot be created because it only has ab See a straightforward version of the property getter.
Implementing an abstract class:
Abstract classes are incomplete because they have methods that don't have a body. If python allows you to create an object for abstract classes, then use that object in case someone calls the abstract method, but there is no actual implementation to call. Therefore, we use an abstract class as a template and extend and build on it as needed before we can use it. Due to the fact that an abstract class is not a concrete class, it cannot be created. When we create an object for an abstract class, error occurs.
Traceback (most recent call last): File "/home/ffe4267d930f204512b7f501bb1bc489.py", line 19, in c = Animal () TypeError: Can' t instantiate abstract class Animal with abstract methods move
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