[Python-Dev] Why both r'' and R'', u'' and U''?

2001年1月14日 14:53:03 +0100

Ka-Ping Yee wrote:
>> Sorry i'm being forgetful -- could someone please refresh my memory:
>> Was there a good reason for allowing both lowercase and capital 'r'
> as a prefix for raw-strings? I assume that the availability of both
> r'' and R'' is what led to having both u'' and U''. 

Right.
> Is there any
> good reason for that either?

No idea... I have never used anything other than the lowercase
versions.

> This just seems to lead to ambiguity and unneeded complexity:
> more cases in tokenize.py, more cases in tokenize.c, more work
> for IDLE, more annoying when searching for u' in your editor.
> (I was about to fix the lack of u'' support in tokenize.py and
> that made me think about this.)
>> What happened to TOOWTDI?
>> Would you believe we now have 36 different ways of starting a string:
>> ' " ''' """
> r' r" r''' r"""
> u' u" u''' u"""
> ur' ur" ur''' ur"""
> R' R" R''' R"""
> U' U" U''' U"""
> uR' uR" uR''' uR"""
> Ur' Ur" Ur''' Ur"""
> UR' UR" UR''' UR"""
>> Would it be outrageous to suggest deprecating the last five rows?

No. + 1 on the idea.

> -- ?!ng
>> [1] We started with 4. Perl has (by my count) 381 ways of starting
> a string literal, so we're halfway there, logarithmically speaking.
> Perl has 757 if you count the fancier operators qx, qw, s, and tr.
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-- 
Marc-Andre Lemburg
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