How to define a static operator<<?

Question

Is it possible to define a static insertion operator which operates on the static members of a class only? Something like:

class MyClass
{
public:
    static         


        

Answer 1

If all the members of MyClass are static, it's possible to return a fresh instance.

However, returning a reference poses a problem. There are two solutions:

• define a static instance
• pass by copy, and not by reference.

The second approach is easiest:

static MyClass operator<< (MyClass, const std::string &token)
{
     MyClass::msg.append(token);
     return MyClass();
}

The first is one line more:

static MyClass& operator<< (MyClass&, const std::string &token)
{
     static MyClass instance;

     MyClass::msg.append(token);
     return instance;
}

Usage is very close to what you want:

MyClass() << "message1" << "message2";

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However, I would not recommend to do this. Why don't you just just use a std::ostringstream? You'll get formatting and some more for free. If you really need global access, declare a global variable.