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

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Bugs item #811604, was opened at 2003-09-24 13:50
Message generated for change (Comment added) made by meyarivan
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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.

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>Comment By: T.Meyarivan (meyarivan)
Date: 2003-09-26 16:34

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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..

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Comment By: Raymond Hettinger (rhettinger)
Date: 2003-09-26 10:05

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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"



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Comment By: T.Meyarivan (meyarivan)
Date: 2003-09-24 14:21

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"".split(None) -> [] 



which is expected because in the case when no sep is

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

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