Factory method(creational)

a factory produces different products according to its input request.

import json
import xml.etree.ElementTree as etree

class JSONConnector:
    def __init__(self, filepath):
        self.data = dict()
        with open(filepath, mode='r', encoding='utf8') as f:
            self.data = json.load(f)

    @property
    def parsed_data(self):
        return self.data


class XMLConnector:
    def __init__(self, filepath):
        self.tree = etree.parse(filepath)

    @property
    def parsed_data(self):
        return self.tree


def connection_factory(filepath):
    """ 工厂方法 """
    if filepath.endswith('json'):
        connector = JSONConnector
    elif filepath.endswith('xml'):
        connector = XMLConnector
    else:
        raise ValueError('Cannot connect to {}'.format(filepath))
    return connector(filepath)

Pros

easy to implement
hard to maintain when its production line become larger

Written on June 18, 2021