[Boost-users] Unique parameter values for interfaces

Subject: [Boost-users] Unique parameter values for interfaces
From: Ryan McConnehey (mccorywork_at_[hidden])
Date: 2009-05-06 02:12:09

I'm currently trying to fortify my class api by "make interfaces easy to 
use correctly and hard to use incorrectly".  I have a class as follows.

class api
{
    api(ConfigName const& configName_, PathName const& pathName_)
    : m_ConfigName(configName_.value)
    , m_PathName(pathName_.value)
    {}

    std::string   m_ConfigName;
    std::string   m_PathName;
};

Both ConfigName and PathName are typedef to a template structure as follows.

template<typename S>
struct ParameterValue
{
    ParameterValue(S value_) : value(value_) {}
    S value
};

typedef ParameterValue<std::string>   ConfigName;
typedef ParameterValue<std::string>   PathName;

I realized later that this method doesn't prevent the swapping of a 
ConfigName with a PathName parameter.  Since both parameters are typedef 
to the same "type" of ParameterValue they're interchangeable.  Is there 
a boost class, library or C++ idiom that would provide what I'm looking 
for?  Since I'm going to be using this concept for other classes I 
build, I'd like something that would easily create parameter classes to 
use but not be interchangeable with other classes of the same type.  I 
know that I could do this with a macro but I'm leaving that for a last 
resort.

Ryan