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

Version 3.5 by chrisby on 2024/03/03 15:17

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
3.5	10	struct Square {
2.4	11	length float
	12	}
	13
3.5	14	struct Circle {
3.2	15	radius float
2.4	16	}
	17
3.5	18	function Circumference(g Object) float {
3.2	19	switch type(g):
	20	case Square:
	21	return 4 * g.length
	22	case Circle:
	23	return 2 * PI * g.radius
2.4	24	}
2.1	25
3.5	26	1. Adding a function Area() with the same anatomy as Circumference() is easy, since it only requires adding new code.
	27	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.
3.3	28
3.4	29	####
	30
2.3	31	#### Object-Oriented Style
2.2	32
3.3	33	interface GeometricObject {
	34	Circumference() float
	35	}
	36
	37	class Square implements GeometricObject {
2.3	38	length float
	39
	40	constructor(length float) {
	41	this.length = length
	42	}
	43
	44	func Circumference() float {
	45	return 4 * this.length
	46	}
	47	}
	48
3.3	49	class Circle implements GeometricObject {
2.3	50	radius float
	51
	52	constructor(radius float) {
	53	this.radius = radius
	54	}
	55
	56	func Circumference() float {
	57	return 2 * PI * this.radius
	58	}
	59	}