Empty std::string in static method initialiser

Question

I am using a static method to initialise the const fields of a class. The static method uses some const variables that are stored in a separate header file. Primitive types are correctly being passed to the static method, but the std::strings are being passed empty. I cannot understand why this is.

After doing some searching I have stumbled upon something called the static initialiser fiasco, but I'm having trouble wrapping my head around it, and can't work out if it is to blame. As the the object is in global scope, is the problem that it is being 'setup' before the std::string class has been 'setup'?

I have tried to replicate a minimal example below:

// File: settings.hpp
#include <string>
const std::string TERMINAL_STRING "Printing to the terminal";
const std::string FILE_STRING "Printing to a file";


// File: printer.hpp
#include <string>
#include <iostream>

class Printer
{
    private:
        const std::string welcomeMessage;
        static std::string initWelcomeMessage(std::ostream&);

    public:
        Printer(std::ostream&);
}

extern Printer::print;


// File: printer.cpp
#include "settings.hpp"

std::string Printer::initWelcomeMessage(std::ostream &outStream)
{
    if (&outStream == &std::cout)
    {
        return (TERMINAL_STRING);
    }
    else
    {
        return (FILE_STRING);
    }
}

Printer::Printer(std::ostream &outStream) :
    message(initWelcomeMessage(outStream)
{
    outStream << welcomeMessage << std::endl;

    return;
}


// File: main.cpp
#include "printer.hpp"

printer print(std::cout);

int main()
{
    return (0);
}

Thanks very much!

score 2 · Accepted Answer · answered May 15 '17 at 20:57

As the the object is in global scope, is the problem that it is being 'setup' before the std::string class has been 'setup'?

Yes.

Have your strings be function-statics, returned by reference from some function, instead.

This is the traditional fix for the static initialisation order fiasco.

Empty std::string in static method initialiser

1 Answers1