python3 raw strings and \u escapes

[Thomas Rachel]

Am 30.05.2012 08:52 schrieb rurpy at yahoo.com:

> This breaks a lot of my code because in python 2
>        re.split (ur'[\u3000]', u'A\u3000A') ==>  [u'A', u'A']
> but in python 3 (the result of running 2to3),
>        re.split (r'[\u3000]', 'A\u3000A' ) ==>  ['A\u3000A']
>
> I can remove the "r" prefix from the regex string but then
> if I have other regex backslash symbols in it, I have to
> double all the other backslashes -- the very thing that
> the r-prefix was invented to avoid.
>
> Or I can leave the "r" prefix and replace something like
> r'[ \u3000]' with r'[ 　]'.  But that is confusing because
> one can't distinguish between the space character and
> the ideographic space character.  It also a problem if a
> reader of the code doesn't have a font that can display
> the character.
>
> Was there a reason for dropping the lexical processing of
> \u escapes in strings in python3 (other than to add another
> annoyance in a long list of python3 annoyances?)

Probably it is more consequent. Alas, it makes the whole stuff 
incompatible to Py2.

But if you think about it: why allow for \u if \r, \n etc. are 
disallowed as well?


> And is there no choice for me but to choose between the two
> poor choices I mention above to deal with this problem?

There is a 3rd one: use   r'[ ' + '\u3000' + ']'. Not very nice to read, 
but should do the trick...


Thomas