How to avoid using a global variable?

Richard Published at Dev

Richard

Getting back into programming after a 20 years hiatus. Been reading that the use of global variables in python is a sign of bad design, but can't figure out a better way of doing it.

Below is a small program that utilizes a global variable 'paused' to determine the state of the music player. This variable is utilized by a couple of functions.

Is there a better way of doing this without utilizing a global variable?

# Global variable to access from multiple functions
paused = False


def play_music():

    global paused

    if not paused:

        try:
            mixer.music.load(filename)
            mixer.music.play()
            statusBar['text'] = 'Playing Music - ' + os.path.basename(filename)
        except:
            tkinter.messagebox.showerror('File not found',
                                         'Melody could not find the file.')
    else:
        mixer.music.unpause()
        paused = False
        statusBar['text'] = 'Playing Music - ' + os.path.basename(filename)


def stop_music():
    mixer.music.stop()
    statusBar['text'] = 'Music stopped'


def pause_music():

    global paused

    if not paused:
        mixer.music.pause()
        paused = True
        statusBar['text'] = 'Music paused'

    else:
        play_music()

Óscar López

You could put all your functions inside a class, and make the "global" variable an attribute. In that way you can share it between methods:

class Player(object):
    def __init__(self):
        self.paused = False
    def play_music(self):
        if not self.paused:
            # and so on
    def pause_music(self):
        if not self.paused:
            # etc.

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