# Composite Type Functions

> 🚧 Status: Function overloading is not implemented yet.

Composite types may contain functions. Just like in the initializer, the special constant `self` refers to the composite value that the function is called on.

```
// Declare a structure named "Rectangle", which represents a rectangle
// and has variable fields for the width and height.
//
pub struct Rectangle {
    pub var width: Int
    pub var height: Int

    init(width: Int, height: Int) {
        self.width = width
        self.height = height
    }

    // Declare a function named "scale", which scales
    // the rectangle by the given factor.
    //
    pub fun scale(factor: Int) {
        self.width = self.width * factor
        self.height = self.height * factor
    }
}

let rectangle = Rectangle(width: 2, height: 3)
rectangle.scale(factor: 4)
// `rectangle.width` is `8`
// `rectangle.height` is `12`
```

Functions support overloading.

```
// Declare a structure named "Rectangle", which represents a rectangle
// and has variable fields for the width and height.
//
pub struct Rectangle {
    pub var width: Int
    pub var height: Int

    init(width: Int, height: Int) {
        self.width = width
        self.height = height
    }

    // Declare a function named "scale", which independently scales
    // the width by a given factor and the height by a given factor.
    //
    pub fun scale(widthFactor: Int, heightFactor: Int) {
        self.width = self.width * widthFactor
        self.height = self.height * heightFactor
    }

    // Declare a another function also named "scale", which scales
    // both width and height by a given factor.
    // The function calls the `scale` function declared above.
    //
    pub fun scale(factor: Int) {
        self.scale(
            widthFactor: factor,
            heightFactor: factor
        )
    }
}
```