gyver-attrs 0.9.4

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Gyver Attrs

Gyver-attrs is a Python library that provides a more flexible and feature-rich alternative to the built-in attrs and dataclasses libraries for defining classes. The main function provided by Gyver-attrs is define, which allows users to define classes with a range of options and features.

Installation

To install Gyver-attrs, you can use pip:

pip install gyver-attrs

Usage

The primary function in Gyver-attrs is define. It takes a list of field definitions and returns a new class with those fields defined as attributes. Here is a basic example:

from gyver_attrs import define, info

@define
class Person:
    name: str
    age: int = info(default=18)

This defines a new class Person with two attributes, name and age.

Features

Gyver-attrs provides a range of features that can be used to customize how classes are defined. These features include:

• maybe_cls: This option allows you to optionally specify the class to be created with the features applied. If it is None, it returns a callable that can wrap classes in the same way.
• frozen: This option replaces __setattr__ and __getattr__ of the class with frozen versions that raise AttributeError when attributes are accessed or modified. This can be useful for creating immutable objects.
• kw_only: This option makes the class's __init__ not accept positional arguments, forcing all arguments to be passed as keyword arguments.
• slots: This option adds a __slots__ to the class with the necessary validations and compliances with inheritance. It also validates possible descriptors with __set_name__ to add the expected name to the __slots__.
• repr: This option adds a __repr__ method to the resulting class.
• eq: This option provides __eq__ and __ne__ methods for the resulting class, comparing all values against each other. Each field can have a parser or opt-out using field(eq=False) or field(eq=my_converter).
• order: This option adds rich comparison support and supports the same mechanism of opt-out/converter as eq.
• hash: This option adds a hash function if all values are hashable and considers the converter from eq as well.
• pydantic: This option adds __get_validators__ to the class to make Pydantic support the classes by default.
• dataclass_support: This option adds __dataclass_fields__ with each field converted to a dataclass.Field before returning it on a dict. This way, the class becomes a drop-in replacement for dataclasses.

Warning: dataclass_fields with pydantic=False will fail when trying to use with pydantic.

Methods

Gyver-attrs will add the following methods to your class.

gyver_attrs: This is a dictionary that maps each attribute name to its corresponding Field object. The Field object contains metadata about the attribute such as its name, type, default value, etc. parse_dict(): This is a method that is used to parse the instance into a dict, recursively. Don't use it directly, instead call asdict(self). iter(): This will yield (key, value) for all fields directly included in the class, and not any fields of nested objects. You can use as dict(self) gserialize(): This is a class method that is used to serialize a dict into an instance of the class. Don't use it directly, instead call fromdict(self). pydantic_validate(): This will validate inputs to support pydantic integration. get_validators(): This is a classmethod to make your class pydantic-compatible. modify_schema(): This is a class method that create schemas for your class when using Pydantic/FastAPI.

Also Gyver-attrs will not override custom defined functions instead, on conflict, you can still find them with the prefix __gattrs_. Examples: __init__ => __gattrs_init__ __hash__ => __gattrs_hash__ __parse_dict__ => __gattrs_parse_dict__

Helper Functions

Gyver-attrs provides helpers to integrate easily with your project

• Shortcuts
  • mutable: same as define but with frozen=True
  • kw_only: same as define but with kw_only=True
• Camel
  • define_camel: same as define but with alias automatically as camel case. This can be either lower or upper camel which can be done by style="upper" or style="lower. By default define_camel uses lower.
• Helpers:
  • call_init: calls __gattrs_init__ without mypy or pyright complaining
  • fields: returns a dict[str, Field] of the class, by returning __gyver_attrs__
• Factory:
  • mark_factory: decorator to mark function as factory
• Converters:
  • fromdict/fromjson: creates instance of class based on a dict/json(using orjson). Use as fromdict(YourClass, mapping) or fromjson(YourClass, yourjson)
  • asdict/asjson: returns your instance as dict/json(using orjson) recursively. Use as asdict(instance, by_alias=True) or asdict(instance, by_alias=False)

Conclusion

Gyver-attrs provides a powerful and flexible way to define classes in Python, with a range of options and features that can be used to customize the behavior of the resulting classes. Whether you're building small scripts or large applications, Gyver-attrs can help you create classes that are tailored to your specific needs.