Simple Python Factory pattern

This module provides a simple way to prevent the direct creation of an instance of a class. Instead a classmethod of this class can be used.

Install

You can install this python module via pip:

pip install simple-factory-pattern

Otherwise the module can be downloaded from PyPI: https://pypi.org/project/simple-factory-pattern/

Usage

1. Import the module:

   from simple_factory_pattern import FactoryPatternMeta
   

2. Create a class that uses the above meta class:

   class NewClass(metaclass=FactoryPatternMeta):
       pass
   

3. Add a classmethod to the new class that returns an instance of the class:

   @classmethod
   def create_instance(cls):
       return NewClass()
   

   You can choose any name for the method. But it must be a classmethod!

   It's also possible to define multiple classmethods. Only in those methods a new instance of the class can be created.

Behavior of the new class

It's not possible to create an instance of the class directly:

instance = NewClass()  # this will fail

This throws a FactoryException (also included in the simple_factory_pattern package).

The only way to get an instance is to call the above definded classmethod:

instance = NewClass.create_instance()  # this works