How to disallow temporaries

Question

For a class Foo, is there a way to disallow constructing it without giving it a name?

For example:

Foo(\"hi\");

And only allow it i

Answer 1

As is, with your implementation, you cannot do this, but you can use this rule to your advantage:

Temporary objects cannot be bound to non-const references

You can move the code from the class to an freestanding function which takes a non-const reference parameter. If you do so, You will get a compiler error if an temporary tries to bind to the non-const reference.

Code Sample

class Foo
{
    public:
        Foo(const char* ){}
        friend void InitMethod(Foo& obj);
};

void InitMethod(Foo& obj){}

int main()
{
    Foo myVar("InitMe");
    InitMethod(myVar);    //Works

    InitMethod("InitMe"); //Does not work  
    return 0;
}

Output

prog.cpp: In function ‘int main()’:
prog.cpp:13: error: invalid initialization of non-const reference of type ‘Foo&’ from a temporary of type ‘const char*’
prog.cpp:7: error: in passing argument 1 of ‘void InitMethod(Foo&)’