An instance is one particular physical instantiation of a class that occupies memory and has data elements. This is what 'self' refers to when we deal with class instances.
An object is everything in Python that you can operate on, like a class, instance, list, or dictionary.
The term instance is very often used interchangeably with the term object, because object refers to a particular instance of a class. It’s a bit of a simplification, because the term object is more general than instance.
The relation between instances and classes is quite simple: we have one class of a given type and an unlimited number of instances of a given class.
Each instance has its own, individual state (expressed as variables, so objects again) and shares its behavior (expressed as methods, so objects again).
To create instances, we have to instantiate the class:
duckling = Duck(height=10, weight=3.4, sex="male")
drake = Duck(height=25, weight=3.7, sex="male")
hen = Duck(height=20, weight=3.4, sex="female")
In the example presented above, we have created three different instances based on the Duck class: duckling, drake and hen. We haven't called any object attributes.
Code
class Duck:def __init__(self, height, weight, sex):
self.height = height
self.weight = weight
self.sex = sex
def walk(self):
pass
def quack(self):
return print('Quack')
duckling = Duck(height=10, weight=3.4, sex="male")
drake = Duck(height=25, weight=3.7, sex="male")
hen = Duck(height=20, weight=3.4, sex="female")