Re: [boost] [BGL] clear_out_edges and MutableIncidenceGraph

Subject: Re: [boost] [BGL] clear_out_edges and MutableIncidenceGraph
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2011-03-23 04:33:52

On Tue, 22 Mar 2011, Shaun Jackman wrote:

> Hi,
>
> adjacency_list implements clear_out_edges, but it's not required by any
> of the graph concepts:
> http://www.boost.org/doc/libs/1_46_1/libs/graph/doc/graph_concepts.html
>
> Could it be added to MutableIncidenceGraph? Actually, now that I check,
> I don't see MutableIncidenceGraph on that page either, although it is in
> graph_concepts.hpp. MutableIncidenceGraph requires remove_edge and
> remove_out_edge_if. clear_out_edges would fit nicely in here, and
> clear_in_edges in MutableBidirectionalGraph.

The problem with that is code might have been written with the previous 
definitions of the concepts, and that code would break if we added 
requirements.  You can use remove_out_edge_if with a predicate that always 
returns true to emulate the behavior, but you'd really want to use a 
sizeof trick to find out if there is an actual clear_out_edges function 
first.

-- Jeremiah Willcock