On 03/30/2012 07:19 PM, Sven Bauhan wrote:
Hi,
I just tried to use boost::lambda to prevent from creating an extra Functor class just for one call. This is the code I tried:
std::deque<LightningSlice>::const_iterator l = std::find_if( m_lightnings.begin(), m_lightnings.end(), boost::lambda::_1.timeslice().contains(time_) );
with typedef std::deque<LightningSlice> LightningQueue; LightningQueue m_lightnings; //!< The lightnings in timeslices
const boost::posix_time::time_period& LightningSlice::timeslice() const { return this->m_period; }
Then I get the error: ../LightningIndex.cpp:38: error: 'const struct boost::lambda::lambda_functor<boost::lambda::placeholder<1> >' has no member named 'timeslice'
What did I wrong?
The type of the placeholder is completely different from the type the placeholder will be eventually be replaced with. This in fact could be any type in the world. What you need to do is bind it: bind( // We want to bind the result of the innermost bind to another // function &boost::posix_time::time_period::contains , bind( // We want to bind the timeslice function to the first argument // passed &LightningQueue::timeslice , _1 ) ) The flavor of bind you want to use is not important. There are currently 3 possibilities in boost (and a 4th if you use C++11): http://www.boost.org/doc/libs/release/libs/bind/ http://www.boost.org/doc/libs/1_49_0/doc/html/lambda/le_in_details.html#lamb... http://boost-sandbox.sourceforge.net/libs/phoenix/doc/html/phoenix/modules/b... Boost.Bind is really just to bind functions. Lambda and Phoenix allow to build more sophisticated unnamed functions. Phoenix is the newest incarnation.
Thanks, Sven _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users