On Tuesday 06 April 2010 08:52:42 Hartmut Kaiser wrote:
How can karma be used to show the result of applying a member function to objects in a container? Consider the following code (which does not compile) to show the real and the imaginary parts of complex numbers stored in a vector:
I added a new example (libs/spirit/example/karma/complex_number_adapt.cpp) demonstrating how to solve this by employing the new FUSION_ADAPT_CLASS macro.
Thank you for the example. While this examples solves the specific problem of displaying complex numbers, it does not address my original question: how can phoenix be used with karma to assign the result of a member function to the attribute of a generator? For example, some complicated classes might have 20 member functions, each of which might be used with some specific grammar; in this case, the approach of using FUSION_ADAPT_CLASS would obscure the clarity of the grammar with a lot of "omit" directives. On other words, how would I replace the following so that it works for the complex number class? double_[ _1 = phoenix::bind( member_func, _val ) ] My understanding (and, apparently, OvermindDL1's as well) of phoenix and karma leads me to believe that the preceding should work. On a related note, the qi tutorial example for parsing into a struct does not show the simplest and, IMHO, the most maintainable way to fill up a struct that may evolve over time or simply has a lot of elements (such as a very application-specific config file parser): int_[ phoenix::bind( &employee::age, _val ) = _1 ] >> quoted_string[ phoenix::bind( &employee::forename, _val ) = _1 ] While the preceding may be inefficient due to use of semantic actions, it generalizes much better since it is essentially self-documenting (compared to at_c). FUSION_ADAPT_STRUCT is nice, but nowhere near as intuitive as above - all in my humble opinion, of course. Regards, Ravi