Is it possible to extend the scope of a variable beyond the if statement without using pointers?

I've got a simple Trace class that logs entering and exiting a method:

#include <iostream>

class Trace
{
public:
    Trace()   {std::cout << "Enter" << std::endl;}

    ~Trace()
    {
        std::cout << "Exit" << std::endl;    
    }
};

void foo()
{
    Trace trace;
    std::cout << "foo..." << std::endl;    
}

int main()
{
    foo();
    return 0;
}

output:

Enter
foo...
Exit

Now I want to be able to enable/disable tracing. So I'll do something like this:

#include <iostream>

class Trace
{
public:
    Trace()   {std::cout << "Enter" << std::endl;}

    ~Trace()
    {
        std::cout << "Exit" << std::endl;    
    }
    static bool enabled;
};
bool Trace::enabled = false;

void foo()
{
    if(Trace::enabled)
        Trace trace;
    std::cout << "foo..." << std::endl;    
}

int main()
{
    Trace::enabled = true;
    foo();
    return 0;
}

The problem is that now the trace instance is scoped to the if statement and therefore the following output is produced:

Enter
Exit
foo...

Is there any way to get the right output in the latter case, without using smart pointers? I want to have the least overhead possible if tracing is disabled.