[Python-Dev] Why both r'' and R'', u'' and U''?
Guido van Rossum
Sun, 14 Jan 2001 12:08:28 -0500
> 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''.
> > Is there any
> > good reason for that either?
> No idea... I have never used anything other than the lowercase
It comes from the numeric literals. C allows 0x0 and 0X0, and 0L as
well as 0l. So does Python (and also 0j == 0J).
> > 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.
Why bother? All that does is outdate a bunch of documentation. I
don't see the extra effort in various parsers as a big deal.
--Guido van Rossum (home page: http://www.python.org/~guido/)