Hi Edward, On Sun, 10 Nov 2002, Edward Diener wrote: eddiel> OK, here are some questions regarding the property map library; eddiel> eddiel> 1) What is a property map ? Is it a template class, a class, a eddiel> template function, a function ?
It is a "concept", as the term is used in the SGI STL docs: http://www.sgi.com/tech/stl/stl_introduction.html It has to do with specifying the contract between generic algorithms (function templates) and the user of such algorithms. If you were looking for some useful concrete component to implement some kind of mapping, then I'm afraid you will be disappointed in the property map library. eddiel> 2) What does the word "property" mean in the context of the name ? Here by property we mean something that is associated with some object. I know this is vague, but there just is not much to the property map concept. eddiel> 3) What is the difference between property map and std::map<> ? std::map<> is a class. property map is a concept (well, a collection of concepts). You can use the boost::associative_property_map adaptor to adapt std::map<> into a type that *models* property map. eddiel> 4) How does one use a property map ? You write function templates with template parameters that have property map as their requirement. eddiel> 5) How does one create a property map of one's own ? Create a class and then define get(), put() and operator[] function for the class. eddiel> 6) What are the prototypes for the get(), put(), and operator[] eddiel> functions, and are these really global functions as the doc eddiel> suggests or are they functions in the boost namespace ? They can live anywhere that argument dependent lookup can find them, which means just about anywhere. eddiel> 7) What do the various categories actually do for property maps ? Like the iterator tags in the C++ std, they allow function templates to dispatch to different code depending on the category of the property map. eddiel> I do not believe that any of these questions are answered clearly eddiel> in the property map documentation although they are all basic eddiel> points which should be explained to the end user. I know there is eddiel> a concept there of mapping keys to values but beyond that the eddiel> documentation seems abstruse at best and needlessly irritating at eddiel> worst. eddiel> eddiel> Please Boosters <g>, think about explaining your ideas to the eddiel> programming world in ways that they understand and can use, rather eddiel> than in metaprogramming terminology which only a select few know. eddiel> Good documentation is as important, in its own way, as good code. I've taken another look at the docs, and I'm afraid I do not see a lot of room for improvement. The docs say pretty much what I said above, and include links to resources where one can learn more about generic programming. The property map library is by nature abstract. The main point of the library is not to provide concrete classes, but instead to describe a whole family of classes so that they can be used interchangeably in function templates (generic algorithms). The property map library is for generic programming, and is described using the terminology of generic programming. If you aren't doing generic programming, then you don't need the property map library. Regards, Jeremy ---------------------------------------------------------------------- Jeremy Siek http://php.indiana.edu/~jsiek/ Ph.D. Student, Indiana Univ. B'ton email: [EMAIL PROTECTED] C++ Booster (http://www.boost.org) office phone: (812) 855-3608 ---------------------------------------------------------------------- _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
