Re: [Boost-users] randomize_property question

Subject: Re: [Boost-users] randomize_property question
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2009-08-14 15:50:39

On Fri, 14 Aug 2009, mcorbion_at_[hidden] wrote:

> Ok so I still can't use the randomize property but I've done a workaround.
> I created an AbstractGraph class which has a m_Graph adjacency_list type
> of graph. And nodes uses the bundled property :
> struct City
> {
>  int pos_X;
>  int pos_Y;
> };
>
>
> My workaround test function uses the property map given to randomly set
> the values, but it's still too specific :
>
> template <typename Graph, typename BundProp,typename RandomGenerator>
> void  AbstractGraph::test(bundle_property_map<Graph,unsigned
> int,BundProp,int> p_PMap, RandomGenerator& p_ewrg){
>
>    AbstractGraph::N_iterator l_NodeStart;
>    AbstractGraph::N_iterator l_NodeEnd;
>    AbstractGraph::GetNodes(l_NodeStart,l_NodeEnd);
>
>    for (; l_NodeStart != l_NodeEnd; ++l_NodeStart) {
>        p_PMap[*l_NodeStart] = p_ewrg();
>    }
> }
>
> called this way in the main :
>
>    mt19937 l_Gen(1988);
>    boost::uniform_int<> RandRange(1,10);
>    boost::variate_generator<boost::mt19937&, boost::uniform_int<> >
> ew2rg(l_Gen, RandRange);
>
>
>    typedef property_map<Graph, int(City::*)>::type t_PMapCity;
>    t_PMapCity l_PMap=get(&City::pos_X,m_Graph);
>    test<Graph,City>(l_PMap,ew2rg);
>
>
> I would like to include the two line that generates the property_map from
> the main to the test function. I've tried this :
>
> template <typename Graph, typename PropertyTagType,typename RandomGenerator>
> void  AbstractGraph::test2( ??? p_PropertyTagName,RandomGenerator& p_ewrg){
>
>    typedef property_map<Graph, PropertyTagType>::type t_PMap;
>    t_PMap l_PMap=get(PropertyTagName,m_Graph);
>    AbstractGraph::N_iterator l_NodeStart;
>    AbstractGraph::N_iterator l_NodeEnd;
>    AbstractGraph::GetNodes(l_NodeStart,l_NodeEnd);
>
>    for (; l_NodeStart != l_NodeEnd; ++l_NodeStart) {
>        p_PMap[*l_NodeStart] = p_ewrg();
>    }
> }
>
> called this way :
>
>    test2<Graph,int(City::*)>(l_Gen, &City::pos_X);
>
> But I can't figure any type for &City::pos_X in order to write the header
> for test2 allowing the function to work with float, char ...

The type of &City::pos_X should be "int City::*" (without the extra 
parentheses); however, argument deduction should pick that up for you 
automatically, both for this code and randomize_property.  The ??? in 
test2 should be PropertyTagType, I believe.

-- Jeremiah Willcock