Re: [boost] [string algo review] overloading on const

From: Beman Dawes (bdawes_at_[hidden])
Date: 2003-10-23 10:16:09

At 10:47 AM 10/23/2003, Pavol Droba wrote:
 >On Thu, Oct 23, 2003 at 11:28:38PM +1000, Thorsten Ottosen wrote:
 >> I would say we have to provide
 >>
 >> template<typename InputContainerT, typename SearchContainerT>
 >>     iterator_range< typename string_algo::container_const_iterator<
 >> InputContainerT >::type >
 >>     find_first(const InputContainerT &, const SearchContainerT &);
 >>...
 >
 >Yes you have overlooked one important point. Your second proposed variant
 >does not make sense and what worse, it is even very dangerous.
 >
 >find_xxx algorithms return a reference into the input container by the
 >means
 >of iterators. Using a temporary as an input, you would get an invalid
 >reference as a result.
 >
 >Returning a reference from a temporary is quite a big error in my 
opinion.

What is the fix? There really needs to be some convenient way to do a 
find_first on a const container. Provide a version that takes begin and end 
iterators? Or is that already done by one of the algorithms in detail that 
you are going to move into boost::algorithm::string?

Something really seems wrong here. If container oriented non-mutating 
algorithm functions like find_first can't be used with const container 
arguments, they may be seen as greatly inferior to the traditional iterator 
oriented non-mutating algorithm functions, which work fine with const 
containers.

--Beman

--Beman