python - 字符串表示中的双引号

Question

这段代码:

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，打印这个字符串:

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

为什么 “But it didn't sing.” 在其他三个项目用单引号引起来时用双引号引起来？

(此代码取自 Learn Python the Hard Way Exercise 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: '"

在那里也添加一个双引号，它将恢复为单引号并转义包含的任何单引号:

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