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Isabel Costa
Isabel Costa

Posted on • Originally published at

Dataclasses in Python are nice!

Couple weeks ago I learned about dataclasses feature in Python. This feature is a nice way to define classes in python. This was introduced in Python 3.7, in particular PEP 557. To use this feature make sure you are running python version 3.7 or above.

Previously, I knew about defining new classes in python using the self.__init__() function. Here's an example of me defining a class Youtuber.

class Youtuber:
    def __init__(self, name: str, categories: list[str]): = name
        self.categories = categories
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Now we can use less boilerplate code to define classes. There is no need to install a separate python library, this will come with python standard library (as long as its > 3.7).

Here's how you can define these now:

from dataclasses import dataclass

class Youtuber:
   """Class for defining youtubers."""
   name: str
   categories: list[str]
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In this example above, I am importing it first from dataclasses import dataclass and then defining it. I created a class definition and used @dataclass annotation to tell to python how it shuold interpret this class definition.

Then I can create this in python, as I would do it anyways, regardless of using @dataclass:

Youtuber("Chris Stuckmann", ["movie-reviews"])
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Here's how you can try this out, using 3 of my favorite youtube channels :)

youtubers = []
youtubers.append(Youtuber("Chris Stuckmann", ["movie-reviews"]))
youtubers.append(Youtuber("Double Toasted", ["movie-reviews"]))
youtubers.append(Youtuber("The Fitness Marshall", ["fitness"]))

for youtuber in youtubers:
    print(f"{}'s categories are: {youtuber.categories}")
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Let's put this all together in a file called and run it! You can copy it from this GitHub gist I created. You should get this output:

$ python  
Chris Stuckmann's categories are: ['movie-reviews']
Double Toasted's categories are: ['movie-reviews']
The Fitness Marshall's categories are: ['fitness']
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Hope you enjoyed this short article!
You can find me on

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