Raw Properties #

Raw properties are the most basic form of properties. They are mimicing regular member variables.

Creation #

A raw property can be created by using the MAKE_PROPERTY() macro:

struct shape :
	tct::cppproperties::properties
{
	MAKE_PROPERTY(x, float);
	MAKE_PROPERTY(y, float);
};

Access #

Raw properties may be used as if they were normal class members:

shape s;
s.x = 24;
s.y = s.x * 2;

std::cout << "x = " << s.x << "\n";
std::cout << "y = " << s.y << "\n";

Furthermore, get_property() and set_property() may be used to access properties:

shape s;

s.set_property<float>("x", 0.27f);

std::cout << "x = " << s.get_property<float>("x") << "\n";

Notifications #

Raw properties provide the ability to register zero or more observers which will be notified when the property value changed. Notifications are implemented through simple callbacks.

The following example registers this as an observer for the x and y properties:

struct shape :
    tct::cppproperties::properties
{
    MAKE_PROPERTY(x, int);
    MAKE_PROPERTY(y, int);

    shape()
    {
        // Register observers
        x.register_observer( [](){ std::cout << "x changed!\n"; } );
        y.register_observer( [](){ std::cout << "y changed!\n"; } );
    }
};

Here we’re registering an “external” observer:

struct shape :
    tct::cppproperties::properties
{
    MAKE_PROPERTY(x, int);
    MAKE_PROPERTY(y, int);
};

void shape_position_changed(const shape& s)
{
    std::cout << "Shape position changed to: " << s.x << ", " << s.y << "\n";
}

int main()
{
    shape s;

    // Register another observer
    s.x.register_observer( [&s](){ shape_position_changed(s); } );
    s.y.register_observer( [&s](){ shape_position_changed(s); } );

    // Set some property values
    s.x = 24;
    s.y = 48;

    return 0;
}