 providing arguments to base.__init__
Hello Ng,
I was playing around with pymedia module
and I succeeded when I used complementation
instead of inheritance .. but then I was
forced to wrap simple methods of sound.Output
like pause/unpause/stop. It works, but
seems to me unnecessary .. and I would like
to grasp why the code below doesn't work
***************************************
import threading, wave, sys,
import pymedia.audio.sound as sound, tkFileDialog
class wavePlayer(threading.Thread, sound.Output):
def __init__(self, filename = None):
if filename == None:
filename = tkFileDialog.askopenfilename()
try:
self.wav = wave.open(filename)
except:
print "something went wrong"
sys.exit(1)
freq, nchannels, format = self.wav.getframerate(),
self.wav.getnchannels(), sound.AFMT_S16_LE
sound.Output.__init__(self, freq, nchannels, format)
threading.Thread.__init__(self)
***************************************
[color=blue][color=green][color=darkred]
>>>p = wavePlayer.wavePlayer()[/color][/color][/color]
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: Output() takes at least 3 arguments (0 given)
can somebody explain why this happens?
I tried to construct more simple example
but there it works fine, here is it
[color=blue][color=green][color=darkred]
>>> class base1:[/color][/color][/color]
.... def __init__(self):
.... self.x = []
.... print "base1"
.... def __del__(self):
.... print "~base1"
....[color=blue][color=green][color=darkred]
>>> class base2:[/color][/color][/color]
.... def __init__(self, a, b):
.... self.x = a * b
.... print "base2"
.... def __del__(self):
.... print "~base2"
....[color=blue][color=green][color=darkred]
>>> class derived(base1, base2):[/color][/color][/color]
.... def __init__(self):
.... print "derived"
.... base1.__init__(self)
.... base2.__init__(self, 5, 7)
.... def __del__(self):
.... print "~derived"
....[color=blue][color=green][color=darkred]
>>> d = derived()[/color][/color][/color]
derived
base1
base2[color=blue][color=green][color=darkred]
>>> dir(d)[/color][/color][/color]
['__del__', '__doc__', '__init__', '__module__', 'x'][color=blue][color=green][color=darkred]
>>> d.x[/color][/color][/color]
35[color=blue][color=green][color=darkred]
>>>
>>> del d[/color][/color][/color]
~derived[color=blue][color=green][color=darkred]
>>>
>>>[/color][/color][/color]
base2.__init__ is called in the same way
sound.Output.__init__ is called
both get multiple arguments
one more curiosity, why doesn't del d, call destructors
of base classes?
Thanks for you answears
--
Daniel
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