On Fri, 18 Dec 2009, Maxime van Noppen wrote:

Jeremiah Willcock wrote:

...

Please tell me if there are any problems, as I have not tested this.

It seems to work. I had to do a little fix to your code though. In the function_property_map you use 'value_type' which isn't defined and which is, I believe :

typedef typename boost::property_traits< function_property_map >::value_type value_type;

OK. It actually should be "typename boost::result_of::type" like what is in the specialization of property_traits.

I also changed the functor type from 'Functor' to 'const Functor&'. It seems to work. What was the rationale for copying it ?

In case your operator()() in the functor is non-const (even though I said I was assuming it was const); switching to a reference is fine.

My functor needs to have a pointer/reference to the graph to be able to get the my_edge object from the edge_descriptor passed to the operator().

OK. Did it work otherwise? -- Jeremiah Willcock

On Fri, 18 Dec 2009, Maxime van Noppen wrote:

Jeremiah Willcock wrote:

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OK. It actually should be "typename boost::result_of::type" like what is in the specialization of property_traits.

Ok fixed it.

...

In case your operator()() in the functor is non-const (even though I said I was assuming it was const); switching to a reference is fine.

And to a const reference ? My operator() is const.

That's what I meant.

...

OK. Did it work otherwise?

I didn't test it on a real world test case yet but I added a std::cout in my functor's operator() and it is called, so I'd say yes.

OK. I just wanted to make sure there weren't any other obvious errors in the code. -- Jeremiah Willcock

On Thu, 5 Sep 2013, potato_research wrote:

I'd like to add, as a future reference, that this approach works well when the bundled property is a pointer. An example could be when you have many graphs with the same underlying vertex set and different edges, so you might want to use pointers to VertexProperty objects as bundled properties.

In particular, VertexProperty could contain a field to be used as the vertex index. See, for example http://pastebin.com/6zpwCb4X for such an object (in the example we don't use pointers, though). In this case we can still use algorithms such as r_c_shortest_paths that expect an index map by adding

value_type operator[](const Arg& arg) const { return f(arg); }

to function_property_map as posted by Jeremiah and edited by Maxime.

Is that something that should be changed in Boost itself? -- Jeremiah Willcock