Bronek Kozicki wrote:
Daniel Frey <daniel.frey@aixigo.de> wrote:
BTW: These things are good to discuss. I think some of this should make it to the documentation :)
I'd like to point your attention to http://std.dkuug.dk/jtc1/sc22/wg21/docs/papers/2004/n1600.html
Most of these ideas are taken from Delphi/C++ Builder, which is understandable since one of the chief architects of .NET, Mr. Hejlsberg, was one of the chief architects of Delphi/C++ Builder before he was hired away by Microsoft. On comp.std.c++ I, and others, argued for properties in C++ a while back along many of the same paths as taken in the article above. The article even repeats the same arguments made for properties which I made on comp.std.c++: syntactic sugar for getXXX()/setXXX() and support for RAD via introspection. I find it amusing that while properties were part of Delphi/C++ Builder 9 years or so, they were considered outside the bounds of C++, but now they have been adapted by Microsoft for .NET in the past 3 years, they are now considered with much more importance and relevance as a real possibility for a future C++.
This is actually not a proposal, just a status of properties as being worked on by C++/CLI group. However please keep in mind, that once it's established, it will go (or may go?) on the fast-track of C++ Committee. C++/CLI properties are going somehow across (hm, I do not know if that's a good word) ICF as proposed in N1611, as both may result in function call taking form: object.member_variable
difference is that properties privide clean notion of getter/setter, while in ICF things appear to be more complicated.
ICF's notion of setting values when it must be done through member functions, what it calls filtering which needs a proxy class, is much more complicated than setting properties via a member function in the property notation as exemplified in the above proposal ( and in Delphi/C++ Builder ). For that reason I favor a separate proposal on properties, as exemplified above, which is outside the bounds of ICF.
On the other side properties do not seem to support template getter/setter .
I feel that properties, purely in the form of setter/getter functions and without any special notation for RAD introspection, can be done using templates and pure C++ notation, with boost::function serving as the glue which ties the property to setter/getter functions. If I can work something out along these lines I will post it.