Python Dataclass Frozen: How does it work?

The Python dataclass frozen is a phenomenon in Python where a dataclass is frozen or can not be modified further. It is advantageous in many aspects as well some of such are that it is usually done to avoid bugs and unnecessary modification in the program. This guide here will help you understand the Python dataclass frozen and ways to use it in the program efficiently to avoid any probable bugs.

What is dataclass?

A dataclass in Python is a class that is used to store information or data values. These are also used to pass information between different parts of a program or system. A frozen dataclass containing a list is not hashable as the list can not be hashable.

What is Python dataclass frozen?

The Python dataclass frozen is a method used to produce immutable sets which prevent from production any type of bugs and unwanted mutations. This also avoids any accidental modifications and also can guarantee consistent outcomes. It also restricts access through its own setattr which can be bypassed by passing it over to an object.

How to use Python dataclass frozen?

As mentioned above the Python dataclass frozen is a method used to make sure that the objects can not be modified. To do so you need to use the “frozen” function to keep the dataclass frozen.

Using Frozenset function

The following set of programs will help you understand as how to use it.

>>> s = set((6, 7, 8))
>>> s
{6, 7, 8}
>>> s.add(9)
>>> s
{6, 7, 8, 9}
>>> fs = frozenset((6, 7, 8))
>>> fs
frozenset({6, 7, 8})
>>> fs.add(9)

In the above statement when the frozen function is used any other element can not be added to the set, which prevents adding any more elements to the set which may cause any type of mutation in the set.

Using frozen function

To make Python frozen dataclass you can also use the “frozen=True” function to make the instances frozen. To use this “frozen=True” function you can take a look at the following codes.

Syntax: –

from dataclasses import dataclass

@dataclass(frozen=True)
class Frozen:
    x: int
    y: int

named_points = {Frozen(0, 0): "Origin"}

This will make the Python frozen dataclass and make immutable sets.

FAQs

What is set?

Sets in Python are one of the built-in data types that are used to store multiple items in a single variable. Items in the sets are unchangeable but the items in the sets can be removed and added. These are usually written within the curly brackets.

Syntax: –

set_1 = {"1", "2", "3"}
print(set_1)

What is Frozenset?

The Frozenset() is a built-in Python function that helps in creating an immutable set object from an iterable. The values in the Frozenset can not be duplicated as the set created by this function is immutable.

What is settatr?

The Python settatr() is a Python function that is used to set a new specified value argument to the specified attribute name of a class or to the attribute of an object.

Syntax: –

class Details:
    name = 'Matt'
    age = 10


d = Details()

print('Name before modification:', d.name)
print('Age before modification:', d.age)

setattr(d, 'name', 'Manny')
setattr(d, 'age', 21)

print('Name after modification:', d.name)
print('Age after modification:', d.age)

Conclusion

This guide here has all the information that can help you in understanding the Python dataclass frozen and how to use it without any issues.

References

1. Frozenset

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