Re: [Boost-users] [lambda] Initializing a std::list of unsigned short points

Subject: Re: [Boost-users] [lambda] Initializing a std::list of unsigned short points
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2009-10-12 14:11:03

AMDG

Ryan McConnehey wrote:
> In my project I'm trying to initialize a std::list of unsigned short 
> pointers.  I've created a couple of simple hand written loops but 
> would like to convert them to use std::for_each.  I've been 
> unsuccessful in the past getting boost::lambda to work with std 
> container of pointers.  In the lambda documentation I know that 
> new_ptr and delete_ptr are need in creating and destroying pointers in 
> lambda functions.  I've provided the hand written loop that does work 
> and the "attempted" conversion to std::for_each.  Any help on the 
> correct implementation for the lambda values would be appreciated.
>
> Ryan
>
> typedef std::list<unsigned short *> ml;
> for (ml::iterator itor = m_list.begin(); itor != m_list.end(); ++itor, 
> startValue++) {
>  *itor = new unsigned short(startValue);
> }
>
> for (ml::iterator itor = m_list.begin(); itor != m_list.end(); ++itor) {
>  delete *itor;
> }
>
> std::for_each(m_list.begin(), m_list.end(), *(bl::_1) = 
> bl::new_ptr<unsigned short>()(bl::var(startValue)++) );
> std::for_each(m_list.begin(), m_list.end(), 
> boost::lambda::delete_ptr(*(boost::lambda::_1)));

Use bind.

std::generate(m_list.begin(), m_list.end(), 
bl::bind(bl::new_ptr<unsigned short>(), bl::var(startValue)++);
std::for_each(m_list.begin(), m_list.end(), bl::bind(bl::delete_ptr(), 
bl::_1));

In Christ,
Steven Watanabe