字符串表示中的雙引號

Question

這個片段：

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."
)

運行時，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.'

為什么"But it didn't sing." 當其他三個項目都是單引號時，請加上雙引號？

（此代碼取自Learn Python the Hard Way Exercise 8。 ）

Answer 1

Python很聰明; 在生成表示時，它將對包含單引號的字符串使用雙引號，以最小化轉義：

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

在那里加上一個雙引號，以及它會恢復到單引號和逃避包含的任何單引號：

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