How to Retrieve Type Names in C Templates for Informative Error Messages?

Retrieve Type Name in C Templates

When developing template classes for parsing data, you may encounter the need to generate informative error messages in case of parsing failures. To provide comprehensive error messages, you may need to know the name of the type that the template function is attempting to convert to.

The code snippet provided below depicts the original code that attempts to retrieve the type name using specializations for strings:

template<typename T> T GetValue(const std::wstring &amp;section, const std::wstring &amp;key)
{
    std::map<std::wstring, std::wstring>::iterator it = map[section].find(key);
    if(it == map[section].end())
        throw ItemDoesNotExist(file, section, key)
    else
    {
        try{return boost::lexical_cast<T>(it->second);}
        //needs to get the name from T somehow
        catch(...)throw ParseError(file, section, key, it->second, TypeName(T));
    }
}

An alternative solution involves using:

typeid(T).name()

The typeid(T) function returns an instance of std::type_info, which provides access to the mangled type name of T. The name() method of std::type_info returns the demangled type name.

Integrating this solution into your code, you can modify the catch block as follows:

catch(...)throw ParseError(file, section, key, it->second, typeid(T).name());

This approach provides a more flexible and efficient way to retrieve the type name without the need for explicit specializations.

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