Wiki source code of Code Example: Data Structure Style vs. Object Style

Version 3.7 by chrisby on 2024/03/03 15:23

version	line-number	content
3.4	1	### Use Cases
	2
	3	This example is intended to demonstrate the extensibility differences between data structures and objects by extending them with
	4
	5	1. an Area() function (extending behavior)
	6	1. a rectangle type (extending data type)
	7
2.4	8	### Data Structure Style
2.1	9
3.7	10	interface GeometricObject {}
	11
	12	class Square implements GeometricObject {
2.4	13	length float
	14	}
	15
3.7	16	class Circle implements GeometricObject {
3.2	17	radius float
2.4	18	}
	19
3.7	20	function Circumference(g GeometricObject) float {
3.2	21	switch type(g):
	22	case Square:
	23	return 4 * g.length
	24	case Circle:
	25	return 2 * PI * g.radius
2.4	26	}
2.1	27
3.7	28	1. Adding an Area() function with a very similar anatomy to Circumference() is easy because it only requires adding new code.
	29	1. Adding a new datatype, Rectangle, is harder because it requires touching existing code, namely any functions like Circumference() or Area() that need to be enabled handle this datatype.
3.3	30
3.4	31	####
	32
2.3	33	#### Object-Oriented Style
2.2	34
3.3	35	interface GeometricObject {
	36	Circumference() float
	37	}
	38
	39	class Square implements GeometricObject {
2.3	40	length float
	41
	42	constructor(length float) {
	43	this.length = length
	44	}
	45
	46	func Circumference() float {
	47	return 4 * this.length
	48	}
	49	}
	50
3.3	51	class Circle implements GeometricObject {
2.3	52	radius float
	53
	54	constructor(radius float) {
	55	this.radius = radius
	56	}
	57
	58	func Circumference() float {
	59	return 2 * PI * this.radius
	60	}
	61	}
3.7	62
	63	1. Adding a function Area() to GeometricObject Interface is hard since all classes implementing
	64	1. Adding a new datatype, Rectangle, is more difficult because it requires touching existing code, namely any functions like Circumference() or Area() that need to be enabled handle this datatype.
	65
	66	### Conclusion
	67
	68	asd
	69
	70