Compile time Meta-programming, with string literals.

Posted by Hassan Syed on Stack Overflow See other posts from Stack Overflow or by Hassan Syed
Published on 2010-04-16T10:29:31Z Indexed on 2010/04/16 10:33 UTC
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I'm writing some code which could really do with some simple compile time metaprogramming. It is common practise to use empty-struct tags as compile time symbols. I need to decorate the tags with some run-time config elements. static variables seem the only way to go (to enable meta-programming), however static variables require global declarations. to side step this Scott Myers suggestion (from the third edition of Effective C++), about sequencing the initialization of static variables by declaring them inside a function instead of as class variables, came to mind.

So I came up with the following code, my hypothesis is that it will let me have a compile-time symbols with string literals use-able at runtime. I'm not missing anything I hope.

template<class Instance>
class TheBestThing {
public:
   void set_name(const char * name_in) {
      get_name() = std::string(name_in);
   }
   void set_fs_location(const char * fs_location_in) {
      get_fs_location() = std::string(fs_location_in);
   }
   std::string & get_fs_location() {
      static std::string fs_location;
      return fs_location;
   }
   std::string & get_name() {
      static std::string name;
      return name;
   }  
};
struct tag {};

int main()
{
   TheBestThing<tag> x;
   x.set_name("xyz");
   x.set_fs_location("/etc/lala");

   ImportantObject<x> SinceSlicedBread;
}

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