Python | Use of slots (original) (raw)

Last Updated : 27 Dec, 2019

When we create objects for classes, it requires memory and the attribute are stored in the form of a dictionary. In case if we need to allocate thousands of objects, it will take a lot of memory space.slots provide a special mechanism to reduce the size of objects.It is a concept of memory optimisation on objects.Example of python object without slots :

Python3 1== `

class GFG(object): def init(self, *args, **kwargs): self.a = 1 self.b = 2

if name == "main": instance = GFG() print(instance.dict)

`

Output :

{'a': 1, 'b': 2}

As every object in Python contains a dynamic dictionary that allows adding attributes. For every instance object, we will have an instance of a dictionary that consumes more space and wastes a lot of RAM. In Python, there is no default functionality to allocate a static amount of memory while creating the object to store all its attributes. Usage of __slots__ reduce the wastage of space and speed up the program by allocating space for a fixed amount of attributes.Example of python object with slots :

Python3 1== `

class GFG(object): slots=['a', 'b'] def init(self, *args, **kwargs): self.a = 1 self.b = 2

if name == "main": instance = GFG() print(instance.slots)

`

Output :

['a', 'b']

Example of python if we use dict :

Python3 1== `

class GFG(object): slots=['a', 'b'] def init(self, *args, **kwargs): self.a = 1 self.b = 2

if name == "main": instance = GFG() print(instance.dict)

`

Output :

AttributeError: 'GFG' object has no attribute 'dict'

This error will be caused.Result of using __slots__:

1. Fast access to attributes
2. Saves memory space