pyrrole

pyrrole is a Role System for Python3 (3.6 and high). It's inspired by the roles implementation in the Moose library of Perl, and its main purpose is to use instead of Mixin classes and multiple inheritance.

ATTENTION: This package is WIP in alpha release

Test

If you would test before install, follow these instructions:

$ git clone https://github.com/MatteoGuadrini/pyrrole.git
$ cd pyrrole
$ python -m unittest test_role.py

Install

For install this package, run pip install:

$ pip install --user pyrrole

Simple role

Here is an example of how a role can be done:

import pyrrole

class FallFromTree(metaclass=pyrrole.Role):
    pass

class Fruit:
    pass

@FallFromTree
class Apple(Fruit):
    pass

apple = Apple()

print(apple.__roles__)

In this example, the Apple class inherits from Fruit but not FallFromTree. FallFromTree is a role class that applies to classes so that they acquire the roles attribute.

Role method

By default, all methods or attribute is inherited from a role class except the dunder methods (ex. __str__).. To force the import of a dunder or normal method, just enclose the method to inherit in a role_method decorator.

import pyrrole

class FallFromTree(metaclass=pyrrole.Role):
    
    @pyrrole.role_method
    def __str__(cls):
        return f"Fall from tree"

class Fruit:
    pass

@FallFromTree
class Apple(Fruit):
    pass

apple = Apple()

print(apple)

More roles

An ordinary class can have multiple roles at the same time.

import pyrrole

@pyrrole.role                                  # use role with decorator
class FallFromTree:
    
    def __init__(self, instance):
        self.trees = list()
        self.trees.append(instance)
    
    def fall(self, tree='tree'):
        return f"Fall from {tree}"
    
@pyrrole.role                                   # use role with decorator
class Deciduous:
    
    def __init__(self, instance):
        self.trees = list()
        self.trees.append(instance)
    
    def clean_leaf(self):
        return f"Clean all leaf"

class Fruit:
    pass

@pyrrole.apply_roles(FallFromTree, Deciduous)               # apply more role at same time
@pyrrole.rename_role_methods(clean_leaf='clean_apple_leaf') # renamed role names
class Apple(Fruit):
    def clean_leaf(self):
        return f"Clean all leaf of apple tree"

apple = Apple()

# apple has role?
pyrrole.has_role(apple, FallFromTree)   # True
pyrrole.has_role(apple, Deciduous)      # True

print(apple.__roles__)                  # ['FallFromTree', 'Deciduous']
print(apple.clean_apple_leaf())         # method renamed from the Deciduous role
print(apple.fall('apple tree'))         # method forced inherited from the FallFromTree role

Open source

pyrrole is an open source project. Any contribute, It's welcome.

A great thanks.

For donations, press this

For me

For Telethon

The Telethon Foundation is a non-profit organization recognized by the Ministry of University and Scientific and Technological Research. They were born in 1990 to respond to the appeal of patients suffering from rare diseases. Come today, we are organized to dare to listen to them and answers, every day of the year.

Adopt the future

Acknowledgments

Thanks to Giacomo Montagner for having the idea. Besides, being a contributor he is a great friend!

Thanks to Mark Lutz for writing the Learning Python and Programming Python books that make up my python foundation.

Thanks to Kenneth Reitz and Tanya Schlusser for writing the The Hitchhiker’s Guide to Python books.

Thanks to Dane Hillard for writing the Practices of the Python Pro books.

Special thanks go to my wife, who understood the hours of absence for this development. Thanks to my children, for the daily inspiration they give me and to make me realize, that life must be simple.

Thanks Python!