On 8/11/2019 2:50 AM, Steven D'Aprano wrote:
On Sat, Aug 10, 2019 at 12:10:55PM -0700, Glenn Linderman wrote:
Or invent "really raw" in some spelling, such as rr"c:\directory\"
or e for exact, or x for exact, or <your favorite character
here>"c:\directory\"
And that brings me to the thought that if \e wants to become an
escape for escape, that maybe there should be an "extended escape"
prefix... if you want to use more escapes, define ee"string where \\
can only be used as an escape or escaped character, \e means the ASCII
escape character, and \ followed by a character with no escape
definition would be an error."
Please no.
We already have b-strings, r-strings, u-strings, f-strings, br-strings,
rb-strings, fr-strings, rf-strings, each of which comes in four
varieties (single quote, double quote, triple single quote and triple
double quote). Now you're talking about adding rr-strings, v-strings
(Greg suggested that) and ee-strings, presumably some or all of which
will need b*- and *b- or f*- and *f- varieties too.
Don't forget the upper & lower case varieties :)
If the plan to deprecate unrecognised escapes and then make them an
exception goes ahead, and I expect that it will, in a few more releases
this "extended escape" ee-string will be completely redundent. If \e is
required, we will be able to add it to regular strings as needed,
likewise for any future new escapes we might want. (If any.)
So unrecognized escapes were deprecated in 3.6. And didn't get removed
in 3.7. And from all indications, aren't going to be removed in 3.8.
What makes you think the same arguments won't happen again for 3.9?
And if we end up keeping the existing behaviour, oh well, we can always
write \x1B instead. New escapes are a Nice To Have, not a Must Have.
"Really raw" rr'' versus "nearly raw" r'' is a source of confusion just
waiting to happen, when people use the wrong numbers of r's, or are
simply unclear which they should use.
I agree that Greg's v is far better than rr, especially if someone tried
to write rfr or rbr.
It's not like we have no other options:
location = r'C:\directory\subdirectory' '\\'
works fine.
But I never thought of that, until Serhiy mentioned it in his reply, so
there are probably lots of other stupid people that didn't think of it
either. It's not like it is even suggested in the documentation as a way
to work around the non-rawness of raw strings. And it still requires
doubling one of the \, so it is more consistent and understandable to
just double them all.
So does this:
location = 'directory/subdirectory/'.replace('/', os.sep)
This is a far greater run-time cost with the need to scan the string.
Granted the total cost isn't huge, unless it is done repeatedly.
Even better, instead of hard-coding our paths in the source code, we can
read them from a config file or database.
Yep, I do that sometimes. But hard-coded paths make good defaults in
many circumstances.
It is unfortunate that Windows is so tricky with backslashes and
forwards slashes, and that it clashes with the escape character, but I'm
sure that other languages which use \ for escaping haven't proliferated
a four or more kinds of strings with different escaping rules in
response.
I agree with this. But Bill didn't consult Guido about the matter.
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