inito 0.0.3b0

A Lombok-inspired boilerplate-elimination library for Python.

inito

A Lombok-inspired boilerplate-elimination library for Python. inito generates constructors, repr, equality/hashing, accessors, and fluent builders once at class-decoration time — never at instance construction or attribute-access time — so the generated classes perform like handwritten ones. Zero runtime dependencies.

Install

pip install inito

or

uv add inito

Quick start

from inito import Data


@Data
class User:
    name: str
    age: int = 0


user = User("Ada", age=30)
print(user)              # User(name='Ada', age=30)
print(user.get_name())   # Ada
user.set_age(31)

@Data also accepts options:

from inito import Data


@Data(frozen=True)
class Point:
    x: int
    y: int

@builder generates a fluent, chainable builder, and composes with @dataclass:

from dataclasses import dataclass
from inito import builder


@builder(to_builder=True)
@dataclass
class Request:
    prompt: str
    temperature: float = 0.7


request = Request.builder().prompt("hello").build()
revised = request.to_builder().temperature(0.9).build()

Type checking

inito ships a mypy plugin that synthesizes every generated member (__init__'s real signature, get_x/set_x, .builder()/Builder/ .to_builder()) so mypy --strict sees your decorated classes correctly — no # type: ignore needed. Enable it in your pyproject.toml or mypy.ini:

[tool.mypy]
plugins = ["inito.typing.mypy_plugin"]

The plugin is mypy-only — pyright has no third-party plugin mechanism. @Data and @AllArgsConstructor additionally ship a .pyi stub marked with the standard typing.dataclass_transform (PEP 681), so pyright also gets a correctly-typed __init__ for those two decorators — no plugin needed, since this is a standard both tools understand natively. get_x/set_x and @Builder's fluent chain remain pyright's gap regardless (see below), since dataclass_transform can only express a constructor signature, not arbitrary generated methods.

Status

Implemented today: @Data (constructor, __repr__, __eq__, __hash__, getters, setters), @Getter (getters only), @Setter (setters only), @NoArgsConstructor (no-argument constructor using field defaults), @AllArgsConstructor (constructor only, every field), @RequiredArgsConstructor (constructor only accepting required fields), @Builder/builder (fluent builder, to_builder=True support), @ToString (__repr__ only — pairs well with @Builder for a readable repr without pulling in @Data's constructor/eq/hash/accessors), and @EqualsAndHashCode (__eq__/__hash__ only).

All of inito.md's Initial Features (v1) are now implemented. See docs/performance.md for benchmarks against handwritten classes, dataclasses, and attrs. See TASKS.md for what's left: docs, CI hardening, and release.

Known limitation: pyright doesn't see most generated members

Every generated member (get_x, set_x, .builder(), .to_builder(), the generated constructor's parameters, ...) is attached to your class via setattr at decoration time — real attributes at runtime. mypy sees all of them correctly once you enable the bundled plugin (the same approach attrs/Pydantic use). pyright has no equivalent third-party plugin mechanism, so get_x/set_x and @Builder's fluent chain still show up as unknown attributes there — your code runs correctly regardless, this is a pyright-only static-typing gap.

@Data's and @AllArgsConstructor's constructors are the exception: pyright does see these correctly, via a .pyi stub marked with the standard typing.dataclass_transform (no inito-specific plugin needed — this is a mechanism pyright supports natively). This doesn't extend to @NoArgsConstructor/@RequiredArgsConstructor: both were deliberately left unmarked, since their real signatures diverge from what dataclass_transform can express (@NoArgsConstructor truly accepts zero arguments rather than "all fields optional"; @RequiredArgsConstructor excludes defaulted fields from __init__ entirely rather than making them optional) — applying the marker there would make pyright silently accept calls the real runtime rejects, which is worse than the current honest gap. Closing the remaining gap for get_x/set_x/@Builder would need a different strategy (e.g. a companion stub generator); tracked in TASKS.md Phase 17, not required for this release.

Known limitations: frozen dataclasses and self-referential fields

Stacking any inito constructor-generating decorator (@Data, @Builder, @AllArgsConstructor, ...) with @dataclass(frozen=True) — in either order — raises dataclasses.FrozenInstanceError. This is expected, not a bug: the generated __init__/build() assign fields with plain self.x = value, which correctly respects the frozen class's blocking __setattr__ rather than silently bypassing the immutability you asked for. If you want inito's own frozen-style behavior, use @Data(frozen=True) (which just omits setters) instead of also stacking @dataclass(frozen=True).

Self-referential type hints (e.g. a linked-list next: Node) also aren't supported: inito resolves annotations eagerly, once, at decoration time — before the class's own name is bound in its module's globals — so a forward reference to the class currently being decorated can't resolve. Forward references to any other, already-defined class work normally.

Contributing

See CONTRIBUTING.md.

License

MIT — see LICENSE.