----- Original Message ----- From: "Reece Dunn" <msclrhd@hotmail.com> To: <boost@lists.boost.org> Sent: Friday, December 31, 2004 4:26 AM Subject: [boost] Re: Object Hierarchies using Interface Types with the BIL
christopher diggins wrote:
On the subject of GUI object hierarchies, I wanted to bring to everyone's attention the Boost Interfaces Library (BIL) currently being developed by Jonathan Turkanis which could be an excellent tool for building a flexible and efficient GUI library. There is a brief introduction to the library on the Boost wiki ( http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?Boost.Interfa... )
The code for declaring the interfaces would look like this:
BOOST_IDL_BEGIN(ILabel) BOOST_IDL_CONST_FN0(GetText, string) BOOST_IDL_CONST_FN0(GetAlignment, align_T) BOOST_IDL_END(ILabel)
What I am trying to get working is:
15: BOOST_IDL_BEGIN(IUIObject) 16: BOOST_IDL_FN4(move, void, g::metric, g::metric, g::metric, g::metric) 17: BOOST_IDL_FN2(move, void, g::metric, g::metric) 18: inline void move( g::point p ) 19: { 20: move( p.x, p.y ); 21: } 22: BOOST_IDL_END(IUIObject)
with the latest CVS of Boost, but with msvc-8.0, I get:
Any suggestions? Is there a version of the BIL that works with the CVS version (or 1.33) of Boost? And is the above valid, since this is the kind of thing I want?
The obvious problem with your code is that the BIL interface is not intended to have any function implementation inside of it. It is in this sense more like a Java interface or a pure abstract base class. So if you want a move functions, I suggest moving them out in a separate class (which I call an extension) template<typename T> struct IUIObjectWrapper : public T { IUIObjectWrapper() : T() { } inline void move(g::point p) { T::move(p.x, p.y); } } typedef IUIObjectWrapper<IUIObject> IUIObjectExtension; This approach actually corrects what I percieve to be a huge flaw with many object libraries, which is the coupling of core functionality and derivable functionality. Also note that a new version of the BIL library is due out in a few days. Christopher Diggins http://www.cdiggins.com http://www.heron-language.com