python __format__ 方法应该如何用于 int？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/2179926/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How is the __format__ method supposed to be used for int?
提问by Juanjo Conti
I saw there was a __format__method but help(int.__format__) doesn't provide any help.
我看到有一种__format__方法，但 help( int.__format__) 没有提供任何帮助。
I also know you're not suppose to call a __method__directly. When is this method called? Which is its argument?
我也知道你不应该__method__直接打电话给 a 。这个方法什么时候调用？它的论据是什么？
采纳答案by Steven Kryskalla
It's used for Py3k's new string formatting scheme.
它用于 Py3k 的新字符串格式化方案。
You can find more info here:
您可以在此处找到更多信息：
http://docs.python.org/whatsnew/2.6.html#pep-3101-advanced-string-formatting
http://docs.python.org/whatsnew/2.6.html#pep-3101-advanced-string-formatting
You are right that it isn't called directly. It's called by str.formator the new formatbuiltin.
你是对的，它没有被直接调用。它由str.format或 新format内置函数调用。
回答by Tor Valamo
It's used when you pass an integer to the format() function. The details elude me, as I can't seem to get it to tell me what exactly the argument is. (Edit: see lost-theory's link)
当您将整数传递给 format() 函数时会使用它。细节让我望而却步，因为我似乎无法让它告诉我争论的确切内容。（编辑：见丢失理论的链接）
Oh, and it only works when the integer is the only argument. If you pass a tuple to format, then the tuple.__format__ function is called, and the int.__str__ or something.
哦，它仅在整数是唯一参数时才有效。如果你传递一个元组来格式化，那么 tuple.__format__ 函数就会被调用，还有 int.__str__ 或其他东西。
'{0}'.format(4)
str(4.__format__(format_spec=''))
