python - 字符串表示中的双引号

Question

这个片段：

formatter = "%r %r %r %r"
print formatter % (
    "I had this thing.",
    "That you could type up right.",
    "But it didn't sing.",
    "So I said goodnight."
)

运行时，打印此字符串：

'I had this thing.' 'That you could type up right.' "But it didn't sing." 'So I said goodnight.'

当其他三个项目在单引号中时，为什么"But it didn't sing."会被放在双引号中？

（此代码取自Learn Python the Hard Way 练习 8。）

Answer 1

Python很聪明；在生成表示时，它将对包含单引号的字符串使用双引号，以尽量减少转义：

>>> 'no quotes'
'no quotes'
>>> 'one quote: \''
"one quote: '"

在那里添加一个双引号，它将恢复为单引号并转义包含的任何单引号：

>>> 'two quotes: \'\"'
'two quotes: \'"'