From: David Abrahams <dave@boost-consulting.com>
Rob Stewart <stewart@sig.com> writes:
I just took a look at> http://boost-consulting.com/boost/libs/parameter/doc/html/index.html> and I have a few comments. Rob, Thanks for your edits. Most were excellent and I integrated themimmediately.
I'm glad to help.
Seeing the function described via table is harder to grasp. I suggest showing the function signature first, but omit the defaults for clarity. That will provide parameter names, in context, which will make the connection to the table simpler.
I'm not sure what to do about that one. The "function signature" is afully general function template, with an overload to handle mutablelvalues for the color_map. If you can suggest something that works,I'm open to it.
I just looked at http://www.boost.org/libs/graph/doc/depth_first_search.html and didn't see a function like the one you're using. However, I can guess at what it ought to look like from your table: template < class Graph , class DFSVisitor , class Root , class ColorMap
void depth_first_search(Graph const & graph, DFSVisitor visitor, Root root_vertex, IndexMap index_map, ColorMap & color); Whether any of the other types should use references to const I can't say. Since color was described as an OUT parameter, I assumed that meant reference to non-const.
I don't know what to do about the hard-to-see vertical ellipsis.Maybe just use . . . instead?
You could use · (a.k.a. ·), but the real issue is to trigger a much larger font size.
You asked: *Where is this assignment occurring?* I tried to clarify: On the other hand, when passing arguments by keyword, the keyword object's assignment operator yields a temporary |ArgumentPack| object, and a conforming C++ compiler will refuse to bind a non-``const`` reference to a temporary.
That does it.
You rewrote this section, and then also seemed confused about what itmeans: a conforming C++ compiler will refuse to bind a non-``const`` reference to a temporary. To support an interface in which the last argument is passed by keyword, there must be a ``depth_first_search`` overload taking its argument by ``const`` reference.
Here's your rewrite: a conforming C++ compiler will refuse to bind a non-``const`` reference to a temporary. To support an interface in which the last parameter is an “out” parameter, and the last argument is passed by keyword, there must be a ``depth_first_search`` overload taking its other arguments by ``const`` reference.
But your rewrite changes the meaning substantially. Maybe you couldtry to understand what I wrote or ask some more questions before wetry to make it better?
Well, I thought I understood what you were trying to say, obviously, or I wouldn't have attempted the rewrite. So, let's see what your version is saying (to me). You say that there must be an "overloading taking its argument...." Note the singular. depth_first_search() takes multiple arguments, so there's an incongruity or I don't understand the overload to which you refer. To make the confusion complete, the code snippet immediately following shows this: template <class A0, class A1, \x{2026}class A4> void depth_first_search(A0 const& a0, A1 const& a1, \x{2026}A4& a4) { core::depth_first_search(dfs_params()(a0,a1,a2,a3,a4)); } I see multiple arguments. It is notable that you've highlighted "const&" and "&" where they appear. That suggests that all of the arguments other than the last should be references to const. So, that leads to "there must be [an] overload taking its other arguments by const reference." What did I miss? -- Rob Stewart stewart@sig.com Software Engineer http://www.sig.com Susquehanna International Group, LLP using std::disclaimer;