sc

supercollider language:
```
MyPoint { var <x,<y;
	*constraint { |v| v = v.asFloat;
		v.inclusivelyBetween(-10,10).if({ ^v }, { Error('Not in [-10,10]').throw }) }
	*new { |x=0,y=0|
		^super.newCopyArgs(*[x,y] collect: this.constraint(_)) }
	x_ { |v| x = this.class.constraint(v) }
	y_ { |v| y = this.class.constraint(v) }
	asString { ^format("[%,%]", x, y) }
}
```

usage:
```
p = MyPoint(-5,5);
p.x = 4;
p.x_(6).y_(2);
p.y_(51); // boom!
```