dataclassish

Tools from dataclasses, extended to all of Python

Python's dataclasses provides tools for working with objects, but only compatible @dataclass objects. 😢
This repository is a superset of those tools and extends them to work on ANY Python object you want! 🎉
You can easily register in object-specific methods and use a unified interface for object manipulation. 🕶️

For example,

from dataclassish import replace  # New object, replacing select fields

d1 = {"a": 1, "b": 2.0, "c": "3"}
d2 = replace(d1, c=3 + 0j)
print(d2)
# {'a': 1, 'b': 2.0, 'c': (3+0j)}

Installation

pip install dataclassish

Documentation

WIP. But if you've worked with a dataclass then you basically already know everything you need to know.

Quick example

In this Example we'll show how dataclassish works exactly the same as dataclasses when working with a @dataclass object.

from dataclassish import replace
from dataclasses import dataclass


@dataclass
class Point:
    x: float
    y: float


p = Point(1.0, 2.0)
print(p)
# Point(x=1.0, y=2.0)

p2 = replace(p, x=3.0)
print(p2)
# Point(x=3.0, y=2.0)

Now we'll work with a dict object. Note that you cannot use tools from dataclasses with dict objects.

from dataclassish import replace

p = {"x": 1, "y": 2.0}
print(p)
# {'x': 1, 'y': 2.0}

p2 = replace(p, x=3.0)
print(p2)
# {'x': 3.0, 'y': 2.0}

# If we try to `replace` a value that isn't in the dict, we'll get an error
try:
    replace(p, z=None)
except ValueError as e:
    print(e)
# invalid keys {'z'}.

Registering in a custom type is very easy! Let's make a custom object and define how replace will operate on it.

from typing import Any
from plum import dispatch


class MyClass:
    def __init__(self, a, b, c):
        self.a = a
        self.b = b
        self.c = c

    def __repr__(self) -> str:
        return f"MyClass(a={self.a},b={self.b},c={self.c})"


@dispatch
def replace(obj: MyClass, **changes: Any) -> MyClass:
    current_args = {k: getattr(obj, k) for k in "abc"}
    updated_args = current_args | changes
    return MyClass(**updated_args)


obj = MyClass(1, 2, 3)
print(obj)
# MyClass(a=1,b=2,c=3)

obj2 = replace(obj, c=4.0)
print(obj2)
# MyClass(a=1,b=2,c=4.0)

Citation

If you found this library to be useful in academic work, then please cite.

Development

We welcome contributions!