On 6/28/2019 10:10 AM, MRAB wrote:
On 2019-06-28 03:40, Glenn Linderman wrote:
On 6/27/2019 3:09 PM, Brett Cannon wrote:
My guess is that without Guido to just ask this will have to go to a
PEP as it changes a built-in.
How does adding two new methods change a built-in?
Now if an extra parameter were added to modify lstrip, rstrip, and
strip to make them do something different, yes.
But adding new methods doesn't change anything, unless someone is
checking for their existence.
My preferred color is pstrip and sstrip (prefix and suffix strip)
since lstrip and rstrip mean left and right.
And maybe there should be a psstrip, that takes two parameters, the
prefix and the suffix to strip.
Such functions would certainly reduce code in a lot of places where I do
if string.startswith('foo'):
string = string[ 3: ];
as well as making it more robust, because the string and its length
have to stay synchronized when changes are made.
lstrip and rstrip remove treat the argument as a set of characters and
can remove multiple characters, so having additional methods pstrip
and sstrip with their very similar names but different behaviours
could be confusing.
I'd prefer to stick with lXXX and rXXX. ldrop and rdrop, maybe?
I was thinking of the change from stripping sets of characters versus
stripping specific sequences of characters, all being strip operations.
But when you point out the confusion and suggest the change of names, I
got to thinking about names, and really, the pstrip/ldrop or
sstring/rdrop operations are more like "replace" than "strip"... there
has to be an exact match.
So maybe a better solution to the functionality needed would be lreplace
and rreplace. On the other hand, the existing .replace( prefix, '',
1 ) almost implements lreplace! It doesn't require it to be a prefix
though :( And there is no option for doing the last N replacements, nor
requiring a single one to be a suffix. The last N replacements could be
done by using a negative N, but it would seem an additional parameter or
new name would be required to do prefix- and suffix-restricted operations.
So my example above could be written as either:
string.lreplace('foo')
string.lreplace('foo', '')
But calling the operations lreplace and rreplace, including the option
of putting in replacement strings, would actually be quite handy. Think
of this:
filename.rreplace('.html', '.css', True )
where the first parameter is the suffix to remove, the second parameter
is a suffix to replace it with, and the third parameter says to add the
replacement even if the first parameter is not found/removed. That's
another operation I find frequently in batch file processing, that
otherwise takes several lines.
As Ned noted in another branch of this discussion, it would be good to
have an update for the 2.7 documentation. And if new functions are
added, by any name, it would be good to have the 3.x documentation
clearly reference in both directions between lstrip and lreplace, and
between rstrip and rreplace (or whatever names).
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