Python classes for exercising the adapter pattern

README.md

Adapter pattern with Python: the music player

Without modifying:

• the Media_player_audio and Media_player_video interfaces
• nor the Media_player_mp4 class

add an adapter that allows the music player to play the sound of an mp4 file.

music_player.py

import os

class Music_player:

    def load_engines(self):
        self.engines = {'.mp3': Media_player_mp3(), '.wav': Media_player_wav()}

    def play(self, filename):
        _, extension = os.path.splitext(filename)
        self.engines[extension].play(filename)

class Media_player_audio:
    def play(self, file_name, audio_format):
        print("music from {} as {}".format(file_name, audio_format))

class Media_player_mp3(Media_player_audio):
    def play(self, file_name):
        super().play(file_name, "mp3")

class Media_player_wav(Media_player_audio):
    def play(self, file_name):
        super().play(file_name, "wav")

class Media_player_video:
    def play(self, file_name, video_format):
        print("video from {} as {}".format(file_name, video_format))

    def play_audio(self, file_name, audio_format):
        print("music from {} as {}".format(file_name, audio_format))

class Media_player_mp4(Media_player_video):
    def play_audio(self, file_name):
        super().play_audio(file_name, "mp4")

def main():
    mp = Music_player()
    mp.load_engines()
    mp.play('baubau.mp3')
    mp.play('baubau.wav')

if __name__ == "__main__":
    main()