On 04/26/2005 04:18 AM, Giovanni P. Deretta wrote:
Hi,
I have been using a small extension to the tuple library 'get' function, that I have found very handy. It allows the extraction of an element of a tuple by specifying its type instead of the index. Example:
given the tuple boost::tuple<type1, type2, type3>
get<type1> returns the first element of the tuple of that type.
This allows one to write more self describing code: you don't need to look up the tuple element type when you find an indexed get function buried deep inside some code. This is especially useful with nested tuples where for example 'get<3>(get<5>(get<0>(my_tuple)))' looks more like line noise than real code :).
Of course this wouldn't work for this tuple: tuple<type1, type1, type3> Maybe if there were some way of associating an enumeration with the tuple, you could: get<f_i>(my_tuple) where fi is some enumerator in, e.g.: enum my_tuple_fields { f_0 , f_1 ... , f_n }; but even then, with nested tuples, there's a possible name conflict amoung the enumerators. Possibly the enumerator names could contain a prefix indicating to which type they belong: enum type0_fields { t0_f_0 , t0_f_1 ... , t0_f_n0 }; enum type1_fields { t1_f_0 , t1_f_1 ... , t1_f_n1 }; Obviously more verbose than I think you want, but it would solve the problem of duplicate types. BTW, I haven't tried it; hence, there may be some flaws in the idea ;)