Python PEP 8文档字符串行长度

Question

我最近开始想，跟着PEP 8走是个好主意。我让我的编辑器显示80列标记，现在正试图换行以适应它。我的问题是。在政治公众人物8中，它说：

Limit all lines to a maximum of 79 characters.

有道理。

[...] For flowing long blocks of text (docstrings or comments), limiting the length to 72 characters is recommended.

为什么是72岁？为什么79对docstring或comments不好？

Answer 1

docstring通常与函数缩进，并以三引号开头和结尾：

def foo(bar, baz):
    """Frobnicate the foobars into baz

    Parameters are ham and spammed.

    """

剩下79-4-3=72个字符。

Answer 2

我相信这是文本文件的宿醉：

At the end of the typewriter age, most designs were geared toward 72 CPL, derived from a pitch of 12 characters per inch, multiplied by 6 inches (see for example IBM Selectric). This would ensure at least 1 inch for each margin, with the U.S. government at the time having standardized on 8 1/2×11" paper.

Source

Many plain text documents still conform to 72 CPL out of tradition.

我认为这就像docstring经常在代码之外的上下文中使用一样，所以遵循大多数纯文本文档用来尽量保持一致的样式是有意义的。例如，man页的文本通常包装为72个字符。通过将docstring限制为72个字符，help()的输出反映了这一点。

This question on Programmers也可能是相关的。

Answer 3

行应该是79个字符的原因是，这样它们就可以容纳80个字符宽的终端（显然它们仍然存在）。在docstring上使用72个字符的原因是，这意味着两边的填充都相等（docstring毕竟是缩进的），并且仍然适合80个字符的宽度。