我正在尝试在class中学习Python，这是我为自己做的练习。我想创建一个可以定期演唱歌曲，也可以反向演唱歌曲的课程。所以这是我输入的内容：
class Song(object):
def __init__(self, lyrics):
self.lyrics = lyrics
def sing_me_a_song(self):
for line in self.lyrics:
print line
def sing_me_a_reverse_song_1(self):
self.lyrics.reverse()
for line in self.lyrics:
print line
def sing_me_a_reverse_song_2(self):
for line in reversed(self.lyrics):
print line
def sing_me_a_reverse_song_3(self):
for line in self.lyrics[::-1]:
print line
bulls_in_parade = Song(["They rally around the family",
"with pockets full of shells"])
#sing it for me
bulls_in_parade.sing_me_a_song()
#1st method of reversing:
bulls_in_parade.sing_me_a_reverse_song_1()
#2nd method of reversing:
bulls_in_parade.sing_me_a_reverse_song_2()
#3rd method of reversing:
bulls_in_parade.sing_me_a_reverse_song_3()
第一种反转方法确实很好，但是我不知道为什么我无法让这两种最后一种方法起作用。
这是我得到的输出：
They rally around the family
with pockets full of shells
----------
with pockets full of shells
They rally around the family
----------
They rally around the family
with pockets full of shells
----------
They rally around the family
with pockets full of shells
这是我想在输出中看到的内容：
They rally around the family
with pockets full of shells
----------
with pockets full of shells
They rally around the family
----------
with pockets full of shells
They rally around the family
----------
with pockets full of shells
They rally around the family
如果在一个单独的函数中定义最后两个方法，它们将正常工作，但我不明白为什么它们在我的课堂上不起作用。
我认为问题应该出在“调用”
lyrics上：self.lyrics()
如果是这样，请帮助我解决此问题。
而且我还必须补充一点，我正在使用python 2.7
最佳答案
好吧，实际上他们确实在工作。
问题是您是第一次更改了数据成员。
您键入self.lyrics.revese（），此后此列表将保持反向。
您可以像这样修复方法：
def sing_me_a_reverse_song_1(self):
tmpLyrics = self.lyrics[:]
tmpLyrics.reverse()
for line in tmpLyrics:
print line
注意：
不要做
tmpLyrics = self.lyrics因为python通过引用传递列表，因此正确的方法是tmpLyrics = self.lyrics[:]