C++ (Qt)
#include <QSize>
struct MyStruct
{
    int width() const;
    static constexpr QSize size{20, 20};
};
 
 
int MyStruct::width() const
{
    return size.width();
}
 
int main()
{
    MyStruct().width();
    return 0;
}
 

int MyStruct::width() const
{
    return MyStruct::size.width();
}

C++ (Qt)
class Size {
	double w,h;
public:
	constexpr Size(double w, double h)
		: w(w), h(h){}
 
	constexpr double width() const{
		return w;
	}
 
	constexpr double height() const{
		return h;
	}
};
 
struct MyStruct
{
    int width() const;
    static constexpr Size size{20, 20};
};
 
 
int MyStruct::width() const
{
    return size.width();
}
 
int main(void) {
	MyStruct().width();
	return 0;
}

C++ (Qt)
struct MyStruct
{
    int width() const;
    constexpr Size size() const
    { return Size(20, 20); }
};

C++ (Qt)
class Size {
	double w,h;
public:
	constexpr Size(double w, double h)
	    : w(w), h(h){}
 
	constexpr double width() const{
		return w;
	}
 
	constexpr double height() const{
		return h;
	}
};
 
struct MyStruct
{
    int width() const;
 
    constexpr Size size() const
    { return Size(20, 20); }
};
 
int MyStruct::width() const
{
	return size().width();
}
 
int main(void) {
	return MyStruct().width();
}