组名不能以数字开头? [英] group name can't start with number?

问题描述

看起来我不能像这样使用正则表达式，

It looks like I can't use regex like this one,

(?P<74xxx>[0-9]+)

重新打包它会引发和错误，

With re package it would raise and error,

sre_constants.error: bad character in group name u'74xxx'

好像不能使用以数字开头的组名，为什么?

It looks like I can't use group names that starts with a number, why?

P.S golang 没有这个问题，很多其他语言也没有这个问题

P.S golang does not have such problem, so does many other languages

推荐答案

鉴于 doc:

组名必须是有效的 Python 标识符

Group names must be valid Python identifiers

作为变量，标识符在 Python 中不能以数字开头.在此处查看有关标识符的更多信息:

As the variables, identifiers mustn't start with a number in Python. See more about identifiers here:

identifier  ::=     (letter|"_") (letter | digit | "_")*
letter      ::=     lowercase | uppercase
lowercase   ::=     "a"..."z"
uppercase   ::=     "A"..."Z"
digit       ::=     "0"..."9"

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