On Fri, Oct 29, 2010 at 11:04 AM, Cromwell Enage
Why would it not be typedef mpl::string<'h','e','l','l','o',' ','w','o','r','l','d'> hello; I would think this was correct, as well.
It probably is, but uses more template parameters, probably leading to longer compile time and bigger pre-processed code (just guesses, I'm no expert). It's also longer to type :)
OR if the example is correct, why could you not simply do typedef mpl::string<'hello world'> hello;
Because that's invalid.
Non-type template arguments can only be constant integers or (maybe in this case) multi-byte characters. A four-byte character value might be the standard limit here. [...]
As [1] points out, using 'abcd' is a "fairly unknown—and arguably somewhat implementation-defined—existence of multi-character literals" feature of C++. [2] further points to STD 6.4.4.4p10 stating it is indeed implementation-defined. But Eric Niebler (templatr-extraordinaire), made it work for known compilers. So yes it's a bit weird at first, but it just works! --DD [1] http://arcticinteractive.com/2009/04/18/compile-time-string-hashing-boost-mp... [2] http://bytes.com/topic/c/answers/739845-multi-character-constant