[Python-bugs-list] [ python-Bugs-811604 ] "string".split behaviour for empty strings

[SourceForge.net]

Bugs item #811604, was opened at 2003-09-24 04:20
Message generated for change (Comment added) made by tjreedy
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=811604&group_id=5470

Category: Python Interpreter Core
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: T.Meyarivan (meyarivan)
Assigned to: Nobody/Anonymous (nobody)
Summary: "string".split behaviour for empty strings

Initial Comment:


"".split() -> []



"".split(' ') -> ['']



It is not clear from the documentation as to what is

the defined behaviour in the above case. To say the

least, it is 

completely counter-intuitive..(splitting an empty

string should

return the list [''] in both cases).



>From stringobject.c, the behaviour of split_whitespace

(i.e split called without sep) and string_split (split

called with sep) is different for empty

strings..perhaps the function split_whitespace needs to

be patched.

----------------------------------------------------------------------

Comment By: Terry J. Reedy (tjreedy)
Date: 2003-09-28 19:50

Message:
Logged In: YES 
user_id=593130

Suggestion: find section of Lib Ref discussing str.split, quote 

existing def, and add succinct sentence that you think is 

needed.  Then change category to 'documentation' so 

appropriate person(s) will see proposal.

----------------------------------------------------------------------

Comment By: T.Meyarivan (meyarivan)
Date: 2003-09-26 07:04

Message:
Logged In: YES 
user_id=30470



Thats so counter intuitive.. :-(



At least the documentation should specify the fact that the

behaviour of "string".split for empty strings is so and so....



The reason this probably never came up ( or mostly ignored

by majority ) is that people probably check if the string is

empty before proceeding to process it.. 



I am not closing the bug before the specific behaviour of

"string".split for empty strings gets to the docs..

----------------------------------------------------------------------

Comment By: Raymond Hettinger (rhettinger)
Date: 2003-09-26 00:35

Message:
Logged In: YES 
user_id=80475

And so it is.  The whitespace version (no args) and the

specified separator version work differently -- the second

version can never return an empty list.



This code has been around for a good while and it is likely

that much code relies on the behavior, so I recommend

classifying it as a beauty spot and closing the bug.



"One man's bug is another man's feature"



----------------------------------------------------------------------

Comment By: T.Meyarivan (meyarivan)
Date: 2003-09-24 04:51

Message:
Logged In: YES 
user_id=30470

"".split(None) -> [] 



which is expected because in the case when no sep is

specified and when sep == None, split_whitespace is called..

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=811604&group_id=5470