bizarre behavior using .lstrip

[Terry Reedy]

"Peter Hansen" <peter at engcorp.com> wrote in message
news:3F6B9B44.9EAD3CF9 at engcorp.com...
> > Does this make any sense at all?  where did the lead c in conn_fee
go?
>
> Based on the behaviour you describe, I would assume lstrip()
> removes, starting at the beginning of the string, all characters
> which are *anywhere* in the argument string you give it, until
> it encounters a character not in that string, at which point it
> stops.

Good call:  from Lib Ref 2.2.6.1 String Methods

lstrip( [chars])

Return a copy of the string with leading characters removed. If chars
is omitted or None, whitespace characters are removed. If given and
not None, chars must be a string; the characters in the string will be
stripped from the beginning of the string this method is called on.

If one wants to remove a leading substring, s[k:] does nicely.
Determining a common prefix to remove is also easy.  The following
does what OP expected:

def rempre(s, pre):
    'assume len(pre) <= len(s)'
    stop = len(pre)
    i = 0
    while i < stop and s[i] == pre[i]:
        i += 1
    return s[i:]

>>> rempre(s, 'chg')
' conn'
>>> rempre(s, 'chg ')
'conn'

Terry J. Reedy