Creating Class Objects from Static Functions

Suppose I have a code as following.

class Color
{
static Color a;
public:
static Color newColor(int r,int g,int b){
        Color color;开发者_运维知识库
        color.setR(r);
        color.setG(g);
        color.setB(b);
        return color;
    }
}

Is it alright to initialize the static variable 'a' using 'Color a = Color::newColor(255,0,0);' I think I read somewhere that creating the instance using this method will create two instances of the class. What is the right way of doing this?

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Yes Color gets instantiated twice

1. the local variable color in newCOlor and
2. the static Color a (since you are returning an object, a member-wise copy will happen at the static variable definition/initialization).

Be sure to put Color::a = Color::newColor(255,0,0); in a cpp/cc file, meaning not in a header file.

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Try this for size:

struct Color
{
    int   R, G, B;
};

Color a = {255, 0, 0};