Why objects suck

class Curve {
String name;
float[] data;
Color color;
}

class Plot {
Curve[] curves;
void addCurve(Curve c);
void removeCurve(String curveName)
}

"No, no, no... you're mixing in style information. Pull the style out of Curve and separate the concerns." Oh. OK...

class Curve {
String name;
float[] data;
}

class CurveStyle {
String curveName;
Color color;
}

class Plot {
Curve[] curves;
void addCurve(Curve c);
void removeCurve(String curveName);
void setCurveStyle(String curveName, CurveStyle style);
}

Well, all right then! I'm sure this in a patterns book somewhere. I feel warm satisfaction with the pure, objectified minimum entropy of my factorization. Until I implement Plot.removeCurve... oh shit... I have to search for all the dangling CurveStyles referring to the curve, and delete them. As OO programmers we do loads of that every day. You come to think of it as natural. The best OO languages have list comprehensions that make it easier to do. That's nice, but it's not enough. The problem is that "objects" aren't a logical model.

Wouldn't it be more "natural" for the dangling CurveStyles to delete themselves when no longer relevant? There's a logical model for that, the relational model:

Style

CurveName	Color
MSFT	Red
GOOG	Blue

Curve

CurveName	Data
MSFT	1,4,-9
GOOG	13,2,22

Logic tells you that the style row cannot exist when the Curve row has been deleted. A foreign key relationship forces the system to delete the style when you delete the curve.

I want my programming language to do that for me, and that's part of what I was wishing for two years ago.