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This article is about how Python uses descriptors. Xiaobian thinks it is quite practical, so share it with everyone for reference. Let's follow Xiaobian and have a look.

Descriptors

Descriptors determine how object properties are accessed. Descriptors are used to customize what happens when you want to reference an attribute.

The way to build a descriptor is to define at least one of the following three methods. Note that instance in the following is the object instance containing the accessed attribute, while owner is the class that is rhetorical by the descriptor.

get(self, instance, owner) -This method is called when the attribute is obtained by (value = obj.attr), and the return value of this method is assigned to the part of the code that requested the attribute value. set(self, instance, value) -This method is called when you want to set the value of an attribute (obj.attr ='value '), it does not return any value. delete(self, instance) -Called when an attribute is deleted from an object (del obj.attr). For an understanding of instance and owner, consider the following code:

class Celsius(object): def __init__(self, value=0.0): self.value = float(value) def __get__(self, instance, owner): return self.value def __set__(self, instance, value): self.value = float(value)class Temperature(object): celsius = Celsius()temp=Temperature()temp.celsius #calls Celsius.__ Get__Thank you for reading! About "python how to use descriptor" this article is shared here, I hope the above content can be of some help to everyone, so that everyone can learn more knowledge, if you think the article is good, you can share it to let more people see it!

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