String literals not allowed as non type template parameters

Question

The following quote is from C++ Templates by Addison Wesley. Could someone please help me understand in plain English/layman\'s terms its gist?

Answer 1

As mentioned in other answers, a string literal cannot be used as a template argument. There is, however, a workaround which has a similar effect, but the "string" is limited to four characters. This is due to multi-character constants which, as discussed in the link, are probably rather unportable, but worked for my debug purposes.

template
class NamedClass
{
    std::string GetName(void) const
    {
        // Evil code to extract the four-character name:
        const char cNamePart1 = static_cast(static_cast(nFourCharName >> 8*3) & 0xFF);
        const char cNamePart2 = static_cast(static_cast(nFourCharName >> 8*2) & 0xFF);
        const char cNamePart3 = static_cast(static_cast(nFourCharName >> 8*1) & 0xFF);
        const char cNamePart4 = static_cast(static_cast(nFourCharName       ) & 0xFF);

        std::ostringstream ossName;
        ossName << cNamePart1 << cNamePart2 << cNamePart3 << cNamePart4;
        return ossName.str();
    }
};

Can be used with:

NamedClass<'Greg'> greg;
NamedClass<'Fred'> fred;
std::cout << greg.GetName() << std::endl;  // "Greg"
std::cout << fred.GetName() << std::endl;  // "Fred"

As I said, this is a workaround. I don't pretend this is good, clean, portable code, but others may find it useful. Another workaround could involve multiple char template arguments, as in this answer.