How do I generate `setX` methods for all private mutable
variables in my class? Do I need to use `__traits`?
I need this for my [tiny-svg](https://github.com/rillki/tiny-svg)
project to generate `setX` methods for all Shapes.
Example:
```D
class Rectangle {
private immutable ...;
private Color fillColor;
private Color strokeColor;
private uint strokeWidth;
this(int x, int y) {...}
mixin(???);
// I need this:
Rectangle setFillColor(Color color) {...}
Rectangle setStrokeColor(Color color) {...}
Rectangle setStrokeWidth(uint color) {...}
}
```
Usage:
```D
new Rectangle(10, 10)
.setFillColor(Colors.white)
.setStrokeColor(Colors.black)
.setStrokeWidth(3);
```
