What is the counterpart for the Python Dataclass exist in Ruby?
In Python it is possible to use dataclasses to tersely define a class without explicitly defining an initialiser / __init__ method for it.
Without dataclasses this would look like this in Python (including arg typing):
class myNewDog2:
def __init__(fur_colour: str, weight: float, is_microchipped: bool, is_asleep:bool=False):
self.fur_colour = fur_colour
self.weight = weight
self.is_microchipped = is_microchipped
self.is_asleep = is_asleep
my_dog = myDog("tri-colour", 19.52, True)
But can be reduced to a form not requiring writing args out twice, using dataclasses:
from dataclasses import dataclass
@dataclass
class myDog2:
fur_colour: str
weight: float
is_microchipped: bool
is_asleep: bool = False # Optional arg / defaults to False
my_dog = myDog("tri-colour", 19.52, True)
This is how an equivalent class definition looks like in Ruby:
class MyDog
def initialize(fur_colour:, weight:, is_microchipped:, is_asleep: false)
@fur_colour = fur_colour
@weight = weight
@is_microchipped = is_microchipped
@is_asleep = is_asleep
end
end
How would I define this class in Ruby just as tersely as in Python? Is it possible to tell Ruby to fill in the blanks on the constructor based on only on a definition of the attributes I want the class to accept and maintain?
A similar way in Ruby seems to be the Data class, which allows you to define simple value object like this:
MyDog = Data.define(:fur_colour, :weight, :is_microchipped, :is_asleep)
And you can create instances with positional or keyword arguments like this:
my_dog = MyDog.new('tri-colour', 19.52, true, false) # or
my_dog = MyDog.new(fur_colour: 'tri-colour', weight: 19.52, is_microchipped: true, is_asleep: false)
Please note that the Data class doesn't support optional arguments, like the is_asleep argument in your example, yet (tested this with Ruby 3.3.1). You always need to provide the same number of arguments as defined.