（python）從回調中查找父函數的參數

如何從callback中找到給函數調用callback函數的參數？（python）從回調中查找父函數的參數

下面的代碼（不完整）將啓動一個調用回調函數的音頻流。它使用pyaudio。

現在，在callback函數中有硬編碼的東西。我試圖擺脫那些。

我讀過pyaudio文檔，我似乎無法將額外的參數傳遞給callback函數。我已經閱讀了inspect python模塊，它的getsource或getouterframes，這對我來說似乎很有趣，希望能夠得到PlayStream函數的參數，但是這導致我無處可去。

如何從callback內參考SoundGeneratorObject參數？

謝謝。

def PlayStream(SoundGeneratorObject): 
    p = pyaudio.PyAudio() 
    stream = p.open(format = p.get_format_from_width(SoundGeneratorObject.WIDTH), 
       channels = SoundGeneratorObject.CHANNELS, 
       rate = SoundGeneratorObject.BITRATE, 
       frames_per_buffer = SoundGeneratorObject.CHUNKSIZE, 
       output = True, 
       stream_callback = callback) 
    stream.start_stream() 
    while stream.is_active(): 
     time.sleep(0.1) 
    stream.stop_stream() 
    stream.close() 
    p.terminate() 

def callback(in_data, frame_count, time_info, status_flags): 
    signal = waves.next() 
    return (signal, pyaudio.paContinue) 

waves = SoundGenerator() 
PlayStream(waves)

來源

2014-12-28 grabaldam

你有沒有考慮命名'SoundgeneratorObje ct' - >'sound_generator_object'當它是一個參數嗎？我有困惑:) –

哈，好的，會做 - 新手程序員在這裏！感謝您的提示 – grabaldam

只要你保留**而不是來回更改，你可以選擇任何約定:) –

你能做這樣的事情來爲你傳遞的回調創建一個範圍嗎？

def callback_maker(waves): 
    def callback(in_data, frame_count, time_info, status_flags): 
     # do stuff (waves is in scope) 
     signal = waves.next() 
     return (signal, pyaudio.paContinue) 
    return callback

如果可以的話，像這樣使用：

stream = p.open(format = p.get_format_from_width(SoundGeneratorObject.WIDTH), 
       channels = SoundGeneratorObject.CHANNELS, 
       rate = SoundGeneratorObject.BITRATE, 
       frames_per_buffer = SoundGeneratorObject.CHUNKSIZE, 
       output = True, 
       stream_callback = callback_maker(SoundGeneratorObject))

來源

2014-12-28 22:13:40

工作正常！非常感謝！我是編碼新手，只是開始掌握基本概念，非常感謝您的幫助！ – grabaldam

@grabaldam沒問題，只要確保你知道爲什麼它的工作:) –

是的，我明白邏輯！謝謝！ – grabaldam

雖然答案已被接受，我想表現出一種替代，如何在技術上則可以通過從父函數訪問參數使用檢查和全局（），此示例將工作：

import inspect 

# as argument 
SoundGeneratorObject = 'Hello World' 

def PlayStream(SoundGeneratorObject): 
    a, b, c = 8, 9, 10 
    print "do a callback" 
    callback(a, b, c) 

def callback(a, b, c): 
    print a, b, c 
    # inspect.stack[1][3] can get the function name that called the callback 
    # inner globals then access to the function by its name 
    # func_code.co_varnames will then get the argument name from the function 
    # since you only have 1 argument, that's why I use index [0] 
    # the outer globals will then access the argument value by its name 
    print globals()[globals()[inspect.stack()[1][3]].func_code.co_varnames[0]] 

# call the parent function 
PlayStream(SoundGeneratorObject) 

do a callback 
8 9 10 
Hello World # successfully get the argument value

來源

2014-12-28 22:42:21 Anzel

（python）從回調中查找父函數的參數

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