Re: Define a mapping from class types to strings?

From:
alan <almkglor@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 21 Nov 2007 06:41:46 -0800 (PST)
Message-ID:
<cef21f96-e244-42bf-8740-bf6cf33a82ca@y5g2000hsf.googlegroups.com>
On Nov 21, 9:30 pm, alan <almkg...@gmail.com> wrote:

Hello world, I'm wondering if it's possible to implement some sort of
class/object that can perform mapping from class types to strings?

Dang, is this so simple that it's not even worth a comment? How *is*
this supposed to be done?

I will know the class type at compile time, like so:
const char *s = string_mapper<thetype>();

However I do not know the string to be associated with the type at
compile time, and will need a way to set up the mapping, to be created
at run time, possibly like so:
void foo(char* some_string_from_runtime){
string_mapper_obj<thetype>.setstring(some_string_from_runtime);

}

Possibly I might want to also mix up the string mappings too, haha,
but I suppose I can do that before they even reach the string mapper.

Maybe something crazy like this? Would this work? (I'm purposefully
glossing over the memory management concerns)
template<class T>
const char* string_mapper_base(bool set, const char* set_to){
  static const char* thestring;
  if(set) internal = set_to;
  return thestring;}

template<class T>
inline const char* string_mapper(){ return string_mapper_base(false,
0);}
template<class T>
inline const char* string_mapper_set(const char* set_to){return
string_mapper_base(true, set_to);}

The above seems to work, except s/string_mapper_base/
string_mapper_base<T>/ in the later two functions.

Which then gives me the problem, how can I make a base class such that
it will be able to get the correct string_mapper_base<T> for derived
classes. I think I'll need a helper class that I'll have to
instantiate (possibly by hand, oh well) for each derived class.

Alternatively I might have to just use template classes. Currently
I'm using inheritance from a base object (so that I can have a list of
objects of various classes by simply getting a vector of pointers to
base classes). Could templates be made to work?

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