python - 似乎无法从子类调用父类的方法

Question

这是我的代码:

from mutagen.easyid3 import EasyID3
from mutagen import File

class MusicFile:
    """A class representing a particular music file.

    Children that are intended to be instantiated must initialize fields for
    the getters that exist in this class.
    """

    def __init__(self, location):
        self.location = location

    def getLocation():
        return self.location

    def getArtist():
        return self.artist

    def getAlbum():
        return self.album

    def getTitle():
        return self.title

###############################################################################


class LossyMusicFile(MusicFile):
    """A class representing a lossy music file.

    Contains all functionality required by only lossy music files. To date, that
    is processing bitrates into a standard number and returning format with 
    bitrate.
    """
    def __init__(self, location):
        super().__init__(location)

    def parseBitrate(br):
        """Takes a given precise bitrate value and rounds it to the closest
        standard bitrate.

        Standard bitrate varies by specific filetype and is to be set by the 
        child.
        """
        prevDiff=999999999
        for std in self.bitrates:
            # As we iterate through the ordered list, difference should be 
            # getting smaller and smaller as we tend towards the best rounding
            # value. When the difference gets bigger, we know the previous one
            # was the closest.
            diff = abs(br-std)
            if diff>prevDiff:
                return prev
            prevDiff = diff
            prev = std

    def getFormat():
        """Return the format as a string.

        look like the format name (a class variable in the children), followed 
        by a slash, followed by the bitrate in kbps (an instance variable in the 
        children). a 320kbps mp3 would be 'mp3/320'.
        """
        return self.format + '/' + self.bitrate


###############################################################################

class Mp3File(LossyMusicFile):
    """A class representing an mp3 file."""

    format = "mp3"

    # Threw a large value on the end so parseBitrate() can iterate after the end
    bitrates = (32000, 40000, 48000, 56000, 64000, 80000, 96000, 112000, 
                128000, 160000, 192000, 224000, 256000, 320000, 999999)

    def __init__(self, location):
        super().__init__(location)

        id3Info = EasyID3(location)
        self.artist = id3Info['artist'][0]
        self.album = id3Info['album'][0]
        self.title = id3Info['title'][0]
        # Once we set it here, bitrate shall be known in kbps
        self.bitrate = (self.parseBitrate(File(location).info.bitrate))/1000

现在，当我尝试实例化 Mp3File 时，它在 Mp3File.__init__() 的最后一行给出错误:

line 113, in __init__
self.bitrate = (self.parseBitrate(File(location).info.bitrate))/1000
NameError: name 'parseBitrate' is not defined

但是，在我看来，应该是在Mp3File中找不到该方法，然后在父类LossyMusicFile中查找该方法，其中它确实存在。

我尝试将该行更改为 self.bitrate = (super().parseBitrate(File(location).info.bitrate))/1000 ，以便它显式使用父类的方法，但我得到同样的错误。这是怎么回事？

如果之前有人问过这个问题或者这是一个愚蠢的问题，我深表歉意，但我在搜索时找不到它，事实上，我很愚蠢。

Answer 1

所有实例方法都必须将 self 作为第一个参数。这里发生的情况是，在 parseBitrate() 中，您将 self 重命名为 br。您需要 parseBitrate(self, br) 才能接受比特率。您还需要将 self 添加到其他方法(如 getFormat())中的参数列表中。

1. 您的代码使用了 thisVariableNamingStyle，它违反了 Python 的官方样式文档 PEP 8 .
2. MusicFile 不会继承 object。 您只能在“新式类”中调用从更高类继承的方法。为了使您的类成为“新式”类，您必须继承object .

此外，获取像 PyCharm 这样的 IDE，它可以在将来自动警告您这些错误。