[Python-ideas] str.split with padding

Steven D'Aprano steve at pearwood.info
Sat Mar 14 05:22:42 CET 2009

On Sat, 14 Mar 2009 01:43:28 pm Lie Ryan wrote:
> And Clover wrote:
> > Here's a simple one I've reinvented in my own apps often enough
> > that it might be worth adding to the built-in split() method:
> >
> >     s.split(sep[, maxsplit[, pad]])
> >
> > pad, if set True, would pad out the returned list with empty
> > strings (strs/unicodes depending on returned datatype) so that the
> > list was always (maxsplit+1) elements long. This allows one to do
> > things like unpacking assignments:
> >
> >     user, hostname= address.split('@', 1, True)
> >
> > without having to worry about exceptions when the number of ‘sep’s
> > in the string is unexpectedly fewer than ‘maxsplit’.
> Can you find a better use case? For splitting email address, I think
> I would want to know if the address turned out to be invalid (e.g. it
> does not contain exactly 1 @s)

What makes you think that email address must contain exactly one @ sign?

Email being sent locally may contain zero @ signs, and email being sent 
externally can contain one or more @ signs. Andy's code:

user, hostname= address.split('@', 1, True)

will fail on syntactically valid email addresses like this:

fred(away @ the pub)@example.com

Steven D'Aprano

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