Python Object-oriented tips

(i), Python duck type

Python is very different as dynamic language inheritance and polymorphism and static language (like Java), for example, in Java, a method, if the passed parameter is a Animal type, then the incoming object must be a Animal type or its subclass, otherwise, the method cannot be called run() . For Python, the incoming type is not necessarily required Animal . We just have to ensure that the incoming object has a run() method, which is the "duck type" in dynamic language, does not emphasize strict inheritance, only need to "look like a duck, even if you are a swan",

So if your object has that method, it's the way Python is oriented to process or function-oriented in the Object!

# coding=utf-8classAnimal (Object): def run (self): print ('Look, there's an animal running.')classDog (Animal): def run (self): print ('Look, it's a dog running.') def eat (self): print ('The dog is eating.')classCar (Object): def run (self): print ('the car started ... ') def gogogo (animal): Animal.run () # animal.eat () GoGoGo (Dog ()) Print ("-- Test Duck type--") GoGoGo (Car ())

(ii), access rights in Python

1). In Python, the variable name starts with a double underscore (__xxx__) and ends with a double underscore, which is a special variable that can be accessed directly, not a private variable, not a property name of the object.'__xxx__'this format;2). To'_xx'The instance variable at the beginning is accessible, but it just tells us that it can be accessed, but as a private variable, not to be accessed arbitrarily;3). The variable name of the instance if the'__xx'Start, this becomes a private variable (Private), can only be accessed internally, "External cannot be accessed directly," and cannot be accessed directly'__xx'is because the Python interpreter'__xx'The variable is changed into'_object__xx'(This is important and can help to understand a lot of problems), so you can still'_object__xx'To access'__xx'Variable.

(iii), pending ING

Python Object-oriented tips