[boost] Re: lexicalCompare

From: Anthony Williams (anthony.williamsNOSPAM_at_[hidden])
Date: 2002-11-18 04:49:25

Gennaro Prota writes:
 > On 14 Nov 2002 12:40:38 +0000, Anthony Williams
 > <anthony.williamsNOSPAM_at_[hidden]> wrote:
 > 
 > >I have uploaded lexical_compare.hpp to the yahoo files area. It contains
 > >implementations of the function template lexicalCompare.
 > 
 > Just a little comment and a couple of questions. The former is
 > actually just a matter of personal preference, so don't feel qualms
 > about ignoring it (well, not that the same advice isn't valid for the
 > questions too :-)

 > BTW once you rewrite it as above you realize that you can
 > further simplify it as:
 > 
 >     for (...) {
 >       if(*first1 < *first2)
 >         return -1;
 > 
 >       else if(*first2 < *first1)
 >         return +1;
 >     }
 >     
 >     if(first2 != last2) // (*)
 >       return -1;
 > 
 >     return first1 != last1;

I think it is clearer to explicitly return +1/0, rather than rely on the
conversion from true/false, but as you say, it is a matter of preference.

 > The questions are: a) as you know the SGI STL has such a template for
 > long time (lexicographical_compare_3way). Did you deliberately choose
 > a different name? Why? 

I wrote the function before I was aware of the SGI implementation.

 > b) Did you really have problems without the
 > casts?

They do no harm, and in the light of the recent discussions on the iterator
concept stress-test classes, I thought it better to put them in, given the
position I was arguing.

Anthony
-- 
Anthony Williams
Senior Software Engineer, Beran Instruments Ltd.
Remove NOSPAM when replying, for timely response.