#!/usr/bin/env python3

# -*- coding: utf-8 -*-

__author__ = 'ipetrash'

# SOURCE: Design Patterns: Strategy — Стратегия

# SOURCE: https://ru.wikipedia.org/wiki/Стратегия_(шаблон_проектирования)

# SOURCE: https://javarush.ru/groups/posts/584-patternih-proektirovanija

from abc import ABC, abstractmethod

class Strategy(ABC):

@abstractmethod

def download(self, file: str):

pass

class DownloadWindowsStrategy(Strategy):

def download(self, file: str):

print("Windows download: " + file)

class DownloadLinuxStrategy(Strategy):

def download(self, file: str):

print("Linux download: " + file)

class Context:

def __init__(self, strategy: Strategy):

self._strategy = strategy

def set_strategy(self, strategy: Strategy):

self._strategy = strategy

def download(self, file: str):

self._strategy.download(file)

if __name__ == '__main__':

context = Context(DownloadWindowsStrategy())

context.download("file.txt") # Windows download: file.txt

print()

context = Context(DownloadLinuxStrategy())

context.download("file.txt") # Linux download: file.txt

context.set_strategy(DownloadWindowsStrategy())

context.download("file.txt") # Windows download: file.txt