Re: [boost] [pool] Warnings in MSVC 7.1 and 8.0

From: Oleg Abrosimov (olegabr_at_[hidden])
Date: 2006-12-02 11:25:37

JOAQUIN LOPEZ MU?Z wrote:
> 
> Oleg, looks like Harmut Kaiser has already fixed this
> problem in the CVS version of pool.hpp. Would you mind
> downloading this newer version from
> 
> http://boost.cvs.sourceforge.net/*checkout*/boost/boost/boost/pool/pool
> .hpp?revision=1.15
> 
> and reporting whether the warnings you had go away?

I've examined it and found the following code snippet:

template <typename UserAllocator>
void * pool<UserAllocator>::ordered_malloc(const size_type n)
{
   const size_type partition_size = alloc_size();
   const size_type total_req_size = n * requested_size;
   const size_type num_chunks = total_req_size / partition_size +
       static_cast<bool>(total_req_size % partition_size);

It suggests that warnings would persist.

The problem is that this lines are copy-pasted in three different places 
and it is a maintainability issue that Harmut Kaiser was catched by.

Second, he replaced this code in two other places by the following:

       const size_type partition_size = alloc_size();
       const size_type total_req_size = n * requested_size;
       const size_type num_chunks = total_req_size / partition_size +
           ((total_req_size % partition_size) ? true : false);

I failed to see how it is better then original version, because the 
problem is in implicit conversion from bool to integer type during 
promotion in operator+

Just replace true with 1 and false with 0 and add an explicit !=0 test 
and you'll have what I've originally proposed:

      size_type calc_num_chunks(const size_type n)
      {
        const size_type partition_size = alloc_size();
        const size_type total_req_size = n * requested_size;
        return total_req_size / partition_size +
            (total_req_size % partition_size) != 0 ? 1 : 0;
      }

Best,
Oleg Abrosimov