cobble

library0.1.4pypypi✓ verified 25d ago

Cobble is a Python library designed for the easy creation of data objects. It automatically implements common methods such as `__eq__` and `__repr__`, simplifying the boilerplate typically associated with simple data-holding classes. The current version is 0.1.4, released on June 1, 2024, and it is actively maintained with a stable release cadence.

serialization

pip install cobble

github ↗package ↗

INSTALL

IMPORT

SIG · COBBLE

cobble

serializationpythonv0.1.4

Install

1.5s avg

Import

—

Disk

16MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.1.4 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.000s · 17.8MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 1.5s · import 0.000s · 18MB

16MB installed

● package 16MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

data

✓ from cobble import data

✗ import cobble @cobble.data

This example demonstrates how to define a simple data object `Song` using the `@cobble.data` decorator and `cobble.field()`. It also shows how to create a more complex structure like an expression tree with `Literal` and `Add` and then process it using a visitor pattern with `cobble.visitor`.

import cobble @cobble.data class Song(object): name = cobble.field() artist = cobble.field() album = cobble.field(default=None) song = Song("MFEO", artist="Jack's Mannequin", album="Everything in Transit") print(song) @cobble.data class Literal: value = cobble.field() @cobble.data class Add: left = cobble.field() right = cobble.field() class Evaluator(cobble.visitor(object)): def visit_literal(self, literal): return literal.value def visit_add(self, add): return self.visit(add.left) + self.visit(add.right) expression = Add(Literal(2), Literal(4)) result = Evaluator().visit(expression) print(f"Evaluation of {expression} is: {result}")

Debug

Known issues

gotchaMutable default arguments in `cobble.field(default=...)` can lead to unexpected shared state across instances. This is a common Python footgun, also applicable to `dataclasses` and `cobble`.

fix

Use `default_factory` for mutable defaults, e.g., `my_list = cobble.field(default_factory=list)`.

affects: All versions

gotchaOverriding `__init__` in a `cobble.data` class will prevent Cobble from automatically generating its own `__init__` method, potentially leading to uninitialized fields or `AttributeError` if not handled carefully.

fix

Prefer using `__post_init__` for custom initialization logic or ensure your custom `__init__` explicitly initializes all fields defined by `cobble.field()`.

affects: All versions

gotchaAccessing fields directly on a `cobble.data` class before instantiation (e.g., `MyClass.field_name`) will result in an `AttributeError` if the field is intended for instances.

fix

Always instantiate the class (e.g., `instance = MyClass(...)`) before attempting to access instance-specific fields. Use `typing.ClassVar` if an attribute truly needs to be a class-level variable and should not be part of the `__init__` generated by `cobble`.

affects: All versions

Upgrade

Version history

0.1.4latest on PyPI · released Jun 1, 2024

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Dependencies

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Agent activity

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Resources

githubhttp://github.com/mwilliamson/python-cobble ↗

packagehttps://pypi.org/project/cobble/ ↗