Metadata-Version: 2.1
Name: attrs-strict
Version: 0.1.2
Summary: Runtime validators for attrs
Home-page: https://github.com/bloomberg/attrs-strict
Author: Erik-Cristian Seulean
Author-email: eseulean@bloomberg.net
License: Apache-2.0
Project-URL: Source, https://github.com/bloomberg/attrs-strict
Project-URL: Tracker, https://github.com/bloomberg/attrs-strict/issues
Project-URL: Documentation, https://github.com/bloomberg/attrs-strict/blob/master/README.md#attrs-runtime-validation
Platform: UNKNOWN
Classifier: Development Status :: 3 - Alpha
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: Apache Software License
Classifier: Operating System :: MacOS :: MacOS X
Classifier: Operating System :: Microsoft :: Windows
Classifier: Operating System :: POSIX
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.6
Classifier: Programming Language :: Python :: 3.7
Classifier: Programming Language :: Python :: 3.8
Classifier: Programming Language :: Python :: Implementation :: CPython
Classifier: Programming Language :: Python :: Implementation :: PyPy
Classifier: Topic :: Software Development :: Libraries
Classifier: Topic :: Software Development :: Testing
Classifier: Topic :: Utilities
Requires-Python: !=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*,!=3.5.*,<4,>=2.7
Description-Content-Type: text/markdown
Requires-Dist: attrs (>=19.1.0)
Requires-Dist: funcsigs (>=1.0.2) ; python_version < "3.5"
Requires-Dist: typing (>=3.7.4.1) ; python_version < "3.5"


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# attrs runtime validation

`attrs-strict` is a Python package that contains runtime validation for [`attrs`]((https://github.com/python-attrs/attrs)) data classes based on the types existing in the typing module.


## Rationale
The purpose of the library is to provide runtime validation for attributes specified in
[`attrs`](https://www.attrs.org/en/stable/) data classes. The types supported are all the builtin
types and most of the ones defined in the typing library. For Python 2, the typing module is
available through the backport found [`here`](https://pypi.org/project/typing/).

## Quick Start
Type enforcement is based on the `type` attribute set on any field specified in an `attrs` dataclass. If the type argument is not specified no validation takes place.

`pip install attrs-strict`

```python
from typing import List

import attr

from attrs_strict import type_validator

>>> @attr.s
... class SomeClass(object):
...     list_of_numbers = attr.ib(
...         validator=type_validator(),
...         type=List[int]
...     )
...

>>> sc = SomeClass([1,2,3,4])
>>> sc
SomeClass(list_of_numbers=[1, 2, 3, 4])

>>> try:
...    other = SomeClass([1,2,3,'four'])
... except ValueError as error:
...    print(repr(error))
attrs_strict._error.AttributeTypeError: list_of_numbers must be
typing.List[int] (got four that is a <class 'str'>) in [1, 2, 3, 'four']
```

Nested type exceptions are validated acordingly, and a backtrace to the initial container is maintained to ease with debugging. This means that if an exception occurs because a nested element doesn't have the correct type, the representation of the exception will contain the path to the specific element that caused the exception.


```python
from typing import List, Tuple

import attr

from attrs_strict import type_validator

>>> @attr.s
... class SomeClass(object):
...     names = attr.ib(
...        validator=type_validator(), type=List[Tuple[str, str]]
...     )

>>> sc = SomeClass(names=[('Moo', 'Moo'), ('Zoo',123)])

attrs_strict._error.AttributeTypeError: names must be
    typing.List[typing.Tuple[str, str]] (got 123 that is a <class 'int'>) in
    ('Zoo', 123) in [('Moo', 'Moo'), ('Zoo', 123)]
```

### What is currently supported ?

Currently there's support for simple types and types specified in the `typing` module: `List`, `Dict`, `DefaultDict`, `Set`, `Union`, `Tuple`, `NewType`, `Callable` and any combination of them. This means that you can specify nested types like `List[List[Dict[int, str]]]` and the validation would check if attribute has the specific type.

`Callable` will validate if the callable function's annotation matches the type definition. If type does not specify any annotations then all callables will pass the validation against it. Support for `Callable` is not available for `python2`.
```python
@attr.s
>>>def fully_annotated_function(self, a: int, b: int)->str:
        ...
>>> def un_annonated_function(a, b):
        ...
>>>class Something(object):
        a = attr.ib(validator=type_validator(), type=typing.Callable)  # Will work for any callable
        b = attr.ib(
            validator=type_validator(), type=typing.Callable[[int, int], str]
        )

>>> Something(a=un_annonated_function, b=fully_annotated_function)
```

`TypeVars` or `Generics` are not supported yet but there are plans to support this in the future.

## Building

For development, the project uses `tox` in order to install dependencies, run tests and generate documentation. In order to be able to do this, you need tox `pip install tox` and after that invoke `tox` in the root of the project.

## Installation

Run `pip install attrs-strict` to install the latest stable version from [PyPi](https://pypi.org/project/attrs-strict/). Documentation is hosted on [readthedocs](https://attrs-strict.readthedocs.io/en/latest/).

For the latest version, on github `pip install git+https://github.com/bloomberg/attrs-strict`.



