Re: [Boost-users] PropertyGraphConcept concept checking errors for an example implicit graph

Subject: Re: [Boost-users] PropertyGraphConcept concept checking errors for an example implicit graph
From: W.P. McNeill (billmcn_at_[hidden])
Date: 2010-06-25 11:24:20

Thanks.  I figured out how that I needed to put a boost namespace around the
whole specialization sometime last night, and after I did everything built
correctly.  The mysterious non-scalar conversion error went away.

Ultimately I think the source of my confusion lay in the fact
that property graph concept types are defined in property_map structures
while all other graph concept types are defined in graph  traits.  I was so
in the habit of adding typedefs inside my graph class I overlooked the fact
that property graphs do something else.

In retrospect this is all clearly spelled out in the documentation, but if I
was confused about it someone else probably will be too.  Hopefully my
sample at http://github.com/wpm/Boost-Implicit-Graph-Example can prevent
someone from going down the same path.

Thanks again for your help.

On Fri, Jun 25, 2010 at 6:55 AM, Jeremiah Willcock <jewillco_at_[hidden]>wrote:

> On Thu, 24 Jun 2010, W.P. McNeill wrote:
>
>  How do I "specialize boost::property_map directly"?  This might be the key
>> to the problem.
>>
>> My current shot in the dark is to try:
>> template<>
>> struct boost::property_map<ImplicitRingGraph, boost::edge_weight_t> {
>> typedef EdgeWeightMap type;
>> typedef EdgeWeightMap const_type;
>> };
>>
>> which gives me the error
>>
>> implicit.hpp:116: error: specialization of ‘template<class Graph, class
>> Property> struct boost::property_map’ in different namespace
>> /opt/local/include/boost/graph/properties.hpp:244: error:   from
>> definition of ‘template<class Graph, class Property> struct
>> boost::property_map’
>>
>
> You need to do:
>
> namespace boost {
>  template <>
>  struct property_map<ImplicitRingGraph, boost::edge_weight_t> {
>    ...
>  };
> }
>
> -- Jeremiah Willcock
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