dan-elias / drytools

Tools for reducing repetition in Python code

DRYtools

version number: 0.1.3

author: Dan Elias

This library provides tools to make Python code shorter, less repetitive and more readable.

Features

• function annotations to coerce and/or validate parameters, and
• decorators and mixins to add groups of Python standard methods to classes

Example

This example provides implementation with and without drytools for a class representing a person's name and age. The required behaviour is:

• The constructor should accept a name and an age
  • age should be coerced to an integer
  • if name is not of type str, raise a TypeError
  • if age is negative or exceeds 200, raise a ValueError
• The full set of comparison methods (ie: __lt__, __eq__ etc) should be implemented reflecting an ordering by age (with alphabetical ordering by name for people with the same age)

Without drytools

from functools import total_ordering

@total_ordering
class person:
    def __init__(self, name, age):
        if not isinstance(name, str):
            raise TypeError(name)
        age = int(age)
        if (age < 0) or (age > 200):
            raise ValueError(age)
        self.name = name
        self.age = age
    def _comp(self):
        return (self.age, self.name)
    def __eq__(self, other):
        return self._comp() == other._comp()
    def __gt__(self, other):
        return self._comp() > other._comp()

With drytools

from operator import ge, le
from drytools import args2attrs, check, compose_annotations, ordered_by

@ordered_by('age', 'name')
class person:
    @compose_annotations
    @args2attrs
    def __init__(self, name: check(isinstance, str, raises=TypeError),
                       age:(int, check(ge, 0), check(le, 200))):
        pass

Getting started

$ pip install drytools

Documentation

https://drytools.readthedocs.io/en/latest/

Contributing

• Issue Tracker: https://github.com/dan-elias/drytools/issues
• Source Code: https://github.com/dan-elias/drytools.git

Continuous integration

https://travis-ci.org/dan-elias/drytools

License

The project is licensed under the GPL-3 license.