Re: [boost] Result of boost::split against empty string changed in post-1.45 release

Subject: Re: [boost] Result of boost::split against empty string changed in post-1.45 release
From: Mateusz Loskot (mateusz_at_[hidden])
Date: 2012-06-11 16:26:33

On 11 June 2012 19:09, Pavol Droba <droba_at_[hidden]> wrote:
> On Mon, 11 Jun 2012 16:58:40 +0200, Mateusz Loskot <mateusz_at_[hidden]> wrote:
>>
>> I have a simple program runs boost::split against empty string.
>> I'm testing with Boost 1.45 and later versions like 1.46 or 1.49.
>> As stated in the // comment below, there is difference in behaviour
>> depending on the Boost version:
>>
>> // https://gist.github.com/2910461
>> #include <cassert>
>> #include <string>
>> #include <vector>
>> #include <boost/algorithm/string/split.hpp>
>> #include <boost/algorithm/string/classification.hpp>
>>
>> int main(int argc, wchar_t* argv[])
>> {
>> Â  Â std::wstring s;
>> Â  Â std::vector<std::wstring> a;
>>
>> Â  Â assert(s.empty());
>> Â  Â boost::split(a, s, boost::is_any_of(L", "), boost::token_compress_on);
>> Â  Â // Boost 1.45: Â true
>> Â  Â // Boost 1.46+: false
>> Â  Â // Â  Assertion failed: s.empty() == a.empty(), file
>> boost_split_empty_string.cpp, line 16
>> Â  Â assert(s.empty() == a.empty());
>> Â  Â return 0;
>> }
>>
>> IMHO, the behaviour exposed in newer versions is a bug.
>> Could anyone shed light on what happened in post-1.46?
>
>
> Please search the boos archives. There was an extensive discussion about
> this particular issue.

Pavol,

You are right, there are some discussions about this behavior,
For example

http://lists.boost.org/Archives/boost/2005/01/79380.php
https://svn.boost.org/trac/boost/ticket/534

and others. Thanks for pointing that.

I have to admit that to me the current behavior is not intuitive.
Also, I have failed to find any example of it in the docs.

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net