On Tue, Oct 28, 2008 at 3:07 PM, Andrey Semashev <andrey.semashev@gmail.com> wrote:
David Abrahams wrote:
on Tue Oct 28 2008, "Stjepan Rajko" <stipe-AT-asu.edu> wrote:
If a ArgumentPack args does not contain an explicit value for _label, args[_label] will return std::string(""). I'm not sure what the right response to e.g., args[label|"something"] should be.
Compilation error?
IMO, it would be better if the "something" value overrode the default-default value designated in the macro above. The keyword can be used with more than one function and some of the functions may want to use different default values.
I like this suggestion.
*3* Make ArgumentPacks constructible from other ArgumentPacks. [...]
The benefit here is that the implementation of window doesn't need to be templated (which is helpful in some cases), and you don't need to write any forwarding functions (or use BOOST_PARAMETER_FUN).
That's very nice. Could be very useful if one wants to hide the function into a separate cpp.
This was exactly what I needed it for :-)
*4* Overloading operator() for typed keywords
Instead of writing, e.g.: window (( _size=size_type(100,100), _position=position_type(0,0) )) , we can write window (( _size(100,100), _position(0,0) )) [...]
Do I understand correctly that in the latter case "window (( _size(100,100), _position(0,0) ))" the arguments are not actually constructed unless they are requested in the window constructor? If so, this is just great! Looking forward to see it in the official Boost.Parameter library.
Yep, you got it.
What I'm also missing is the ability to iterate through an argument pack with the ability to acquire argument names. Basically, I want to be able to transform an argument pack into something like a map< string, any >. I can see there is some support for argument names, but I don't see how I could iterate through the argument pack.
I think it would be useful to write an include file that makes ArgumentPacks conforming fusion sequences. With that, what you're trying to solve should be doable using fusion::for_each. Thanks for your feedback! Stjepan