On 7/1/2019 8:28 PM, Terry Reedy wrote:
On 7/1/2019 1:57 PM, Chris Barker via Python-Dev wrote:
This was quite extensively discussed on python-ideas recently:
https://mail.python.org/archives/list/python-id...@python.org/thread/RJARZSUKCXRJIP42Z2YBBAEN5XA7KEC3/#WIRID57ESUFUAQQQ6ZUY2RK5PKQQYSJ3
The claim of 'inconsistent results' is based on not reading the doc.
(I'm finding it hard to find a good thread view in the new interface
-- but that will get you started)
My memory of that thread is that there was a lot of bike shedding,
and quite a lot of resistance to adding a couple new methods, which I
personally never understood (Not why we don't want to add methods
willy-nilly, but why there was this much resistance to what seems
like an low-disruption, low maintenance, and helpful addition)
I did not read much of the thread, but the proposal is to wrap a
near-trivial expression (2 operations) or replace a current method
call with a method call than is more or less the same len as what it
replaces.
>>> 'prefix_more_suffix'[len('prefix'):] # if know s begins with p
'_more_suffix'
>>> 'prefix_more_suffix'.replace('prefix', '')
'_more_suffix'
>>> 'prefix_more_suffix'.strip_pre('prefix') # proposed
Your example isn't equivalent: .replace would replace multiple instances
of prefix, not necessarily at the beginning. The .strip_pre (however
spelled) would strip one instance, only if it is at the beginning.
The more I thought about this, the more I think a more functional goal
is a variation of replace that works only on one end or the other,
rather than a variation of strip. I outlined that in a different branch
in this thread.
The other documentation issue I noticed is that the 2nd and 3rd
parameters to startswith and endswith are not fully documented.
Typically startswith and endswitch are in the logic prior to the
strip/replace operation, and typically only use the first parameter, but
looking at their documentation as part of this discussion, I found it
lacking.
A method could raise instead of returning the string as-is if the
prefix is not really a prefix. How often is this needed? The most
common end deletions are whitespace, which the current .strip handles
correctly.
raising wouldn't be helpful in most of the situations where I use this
logic... it would require a more complex flow control than the if
startswith path in the current situation.
Yes, I use strip more frequently, but if startswith: chop_prefix
operation (and the other end too) happens an awful lot.
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