Re: [Boost-users] [BGL] adding behaviour to nodes and edges

On Jun 14, 2005, at 1:35 PM, martin f krafft wrote:

also sprach Doug Gregor [2005.06.14.2006 +0200]:

...

property map). If you have a const graph or property map, you get const property values; non-const graphs and property maps give non-const property values. If we put the properties in the descriptors, we need to have const and non-const descriptors,

Your explanation makes perfect sense. One thing I am left to wonder though is why edge descriptors aren't const by definition. After all, I should not be allowed to modify them at all. Moreover, I should not be allowed to modify them if part of a const graph.

edge descriptors are meant to be "opaque"; the documentation doesn't say anything about their structure, so there are no guarantees about what they contain. In truth, everything in an edge description that doesn't involve copying or constructing should be private, but that couldn't be done when the BGL was written because most compilers couldn't handle templated friends. Doug