On Mon, Jul 27, 2009 at 9:54 AM, Stewart, Robert<Robert.Stewart@sig.com> wrote:
Fatih wrote:
I'm very interesting in this problem ,I think it's very hard to implement the string to enum translation at compile time, I have no ideas about it, wish you can work it out.
It is not difficult, though it requires registering the string against the value in a map during runtime initialization. (We use a library initialization mechanism, called from main(), to trigger such initialization.)
Well that's of course not a compile time solution though if it requires runtime initialization. The approach taken by my solution (which I still haven't uploaded to vault btw) scopes the enums with a namespace, and inside the namespace provides a template specialization for each value in the enum that was specified by one of the MAP_ENUM() macro invocations. For example, given the followign enum definition: typedef enum { Value1, Value2 } Enum1; Then the macro sequence: BEGIN_ENUM_MAP(Enum1, map1) ENUM_MAP(Value1, "this is a test") ENUM_MAP(Value2, "test2") END_ENUM_MAP() would generate the following code: namespace map1 { template<Enum1 e> class lookup {}; template<> class lookup<Value1> { static const char* name; }; const char* lookup<Value1>::name = "this is a test"; template<> class lookup<Value2> { static const char* name; }; const char* lookup<Value2>::name = "test2"; } Now, using code such as the following: std::string test = map1::lookup<Value1>::name; which with optimizations on will generate identical code as doing: std::string test = "test2"; Of course my macros generated additional code as well to create and initialize static runtime lookup maps, but due to the inclusion of everything in every translation unit I agree it's not appropriate in its current form. When I get time to re-think about it perhaps I'll address that issue and then consider uploading it.