Abstract Factories
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A collection of classes to support the Abstract Factory design pattern, providing a clear abstraction
layer for scalable data in dynamic environments.
abstract_factories
will auto-register viable items from any given python module and/or path.
- Tested on Python 3.7 - 3.12
- Functional on Python 2.7
Wait - what? Python 2.7? What year is this?
I often work professionally on legacy systems that are too
fragile or large to update.
Providing there's no functional or notable impact
supporting 2.7, I have no reason to ignore its existence yet.
Installation
pip install abstract-factories
Usage
Initialize AbstractTypeFactory or AbstractInstanceFactory with an abstract type.
Optionally, provide the attribute/method name to identify items by name (and optionally version).
Registering items can be done directly.
from abstract_factories import AbstractTypeFactory
class AbstractVehicle(object):
def start(self):
raise NotImplementedError()
class Car(AbstractVehicle):
def start(self):
print('Vrooom...')
type_factory = AbstractTypeFactory(AbstractVehicle)
type_factory.register_item(Car)
assert type_factory.get('Car') is Car
By default, items are referred to by class name, unless a name_key is provided.
Abstract factories can automatically register items found in given python modules or paths.
from abstract_factories import AbstractTypeFactory
from . import my_vehicle_package
type_factory = AbstractTypeFactory(my_vehicle_package.AbstractVehicle)
type_factory.register_module(my_vehicle_package)
assert type_factory.get('Car') is my_vehicle_package.Car
type_factory.register_path('c:/Users/user/downloads/other_vehicles')
In some use-cases, instances are a much better fit for the type of data you want to use in your factory (a factory of factories?).
In that case, use AbstractInstanceFactory
.
from abstract_factories import AbstractInstanceFactory
class AbstractVehicle(object):
def __init__(self, make=None):
self.make = make
def start(self):
raise NotImplementedError()
class Car(AbstractVehicle):
def start(self):
print('Vrooom...')
honda = Car('Honda')
instance_factory = AbstractInstanceFactory(AbstractVehicle, name_key='make')
instance_factory.register_item(honda)
assert instance_factory.get('Honda') is honda
Registration:
Register viable items directly.
type_factory.register_item(AbstractSubclass)
instance_factory.register_item(AbstractSubclass())
Find and register any viable items found in the module's locals.
type_factory/instance_factory.register_module(module)
Find and register any viable items found in any nested python file from a dynamic
import. Some limitation using relative imports.
type_factory/instance_factory.register_path(r'c:/tools/tool_plugins')
type_factory/instance_factory.register_path(r'c:/tools/tool_plugins/plugin.py')
Practical Applications
Some examples of practical applications for abstract_factories
in a production environment.
Data Validation and Contextual Modification
Use multiple factories together to design scalable Validation, Publishing, Batching, Playlist
etc frameworks.
The simplicity of this design allows for quick iteration during development, conditional
validation, scalability and more.
See the simple_validation example.
Content Creation - Rigging
Useful for managing production needs in Film, TV, and Games, allowing easy modifications and versioning of components.
Easily support and modify rig component behaviours during production.
See the rig_factory example.
Advanced:
These topics are for more advanced usage of abstract_factories
.
Contextual get
:
Instead of a str
type name_key
or version_key
value, you can instead provide a callable. This will be used to
determine each item's name and/or version.
This is especially useful when the context of an item's name or version lies outside the Factory's remit.
! Warning: A conditional name_key
or version_key
may result in unexpected behaviour if not managed correctly.
Testing
.tests/
directory contains examples for;
- Adding, removing & comparing items directly.
- Adding, removing & comparing items found in modules and/or paths.
Further Information
Abstract factories is influenced by https://github.com/mikemalinowski/factories.
License
This project is licensed under the MIT License.