2024-07-12
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This article mainly introduces class methods and static methods in classes and objects in Python, as well as their definitions, characteristics, application scenarios, and usage methods, and compares the two.
Brief Analysis of CM3 Debugging System
After half a month of hard work, a summary of the embedded technology stack is released
You can visit the following link to download the document:
https://github.com/leezisheng/Doc
This document mainly introduces how to use Python for object-oriented programming, and requires readers to have a basic understanding of Python syntax and MCU development. Compared with other blogs or books that explain Python object-oriented programming, this document is more detailed and focuses on embedded host computer applications. It uses common serial port data transmission and reception, data processing, dynamic graph drawing, etc. of host and slave computers as application examples, and uses Sourcetrail code software to visualize the code for easy understanding by readers.
The relevant sample code acquisition link is as follows:https://github.com/leezisheng/Python-OOP-Demo
Taking the SensorClass class as an example, the methods defined in the class, such as InitSensor, StartSensor, StopSensor, etc., areObject Methods, which means that these methods are messages sent to the object and call the properties in the object.In fact, not all methods we write in a class need to be object methods. Some methods in a class do not need to call object properties. For example, in the InitSensor method, we may need to determine whether the current COM port exists. Obviously, this method has nothing to do with the sensor object.
For another example, we define a "Triangle" class, which constructs a triangle by passing in three side lengths, and provides methods for calculating the perimeter and area. However, the three side lengths passed in may not necessarily construct a triangle object, so we can first write a method to verify whether the three side lengths can form a triangle. This method is obviously not an object method, because the triangle object has not been created when this method is called (because we don't know whether the three sides can form a triangle), so this method belongs to the triangle class but not to the triangle object. We can useStatic methodsTo solve this type of problem, the code is as follows.
@staticmethod
_# 判断传感器ID号是否正确：这里判断ID号是否在0到99之间_
def IsTrueID(id:int = 0):
if id >= 0 and id <= 99:
return True
else:
return False
Static methods are actually the functions we have learned. The only difference between them is that static methods are defined in the class space (class namespace), while functions are defined in the space where the program is located (global namespace). Static methods do not have special parameters such as self and cls, so the Python interpreter will not bind any class or object to the parameters it contains. Because of this, no class attributes or class methods can be called in the static methods of a class. Here we define the IsPort static method to determine whether the sensor ID number is correct. Static methods need to be modified with @staticmethod. Static methods can be called using either class names or class objects, for example:
_ # 设置ID号_
id = 1
_ # 判断ID号是否符合格式_
if SensorClass.IsTrueID(id):
s = SensorClass()
else:
print("Sensor Init False")
Similar to static methods, Python can also define class methods in classes. The first parameter of a class method is named cls, which represents an object of information related to the current class (the class itself is also an object, and is sometimes called the class metadata object). Through this parameter, we can obtain information related to the class and create an object of the class. Python will automatically bind the class itself to the cls parameter (note that it is not the class object that is bound). In other words, when calling a class method, we do not need to explicitly pass in the cls parameter.
Class methods need to be modified with the @classmethod modifier. We define the class method MasterInfo in MasterClass. The sample code is as follows:
@classmethod
def MasterInfo(cls):
print("Info : "+str(cls))
print(MasterClass.MasterInfo())
I have devoted myself to the research of technology for more than 30 years. I am proficient in various languages such as Java, Linux, JavaScript, PHP, CSS, etc. I have made many contributions in the field of open source. I have established a developer documentation site to share some problems in technology development for everyone to read.
