Changes for page Code Example: Data Structure Style vs. Object Style

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...	...	@@ -1,42 +8,28 @@
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		-
8	8	### Data Structure Style
9	9
10		- interface GeometricObject {}
11		-
12		- class Square implements GeometricObject {
	3	+ type Square struct {
13	13	length float
14	14	}
15	15
16		- class Circle implements GeometricObject {
17		- radius float
	7	+ type Circle struct {
	8	+ length float
18	18	}
19	19
20		- function Circumference(g GeometricObject) float {
21		- switch type(g):
22		- case Square:
23		- return 4 * g.length
	11	+ func Area(g GeometricObject) float {
	12	+ switch (g.type()):
24	24	case Circle:
25		- return 2 * PI * g.radius
	14	+ return
	15	+ case Square:
	16	+ return ...
26	26	}
	18	+
	19	+ func Circumference(g GeometricObject) float {
	20	+ ...
	21	+ }
27	27
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.
30		-
31		-####
32		-
33	33	#### Object-Oriented Style
34	34
35		- interface GeometricObject {
36		- Circumference() float
37		- }
38		-
39		- class Square implements GeometricObject {
	25	+ class Square {
40	40	length float
41	41
42	42	constructor(length float) {
...	...	@@ -43,12 +43,16 @@
43	43	this.length = length
44	44	}
45	45
	32	+ func Area() float {
	33	+ return this.length * this.length
	34	+ }
	35	+
46	46	func Circumference() float {
47	47	return 4 * this.length
48	48	}
49	49	}
50	50
51		- class Circle implements GeometricObject {
	41	+ class Circle {
52	52	radius float
53	53
54	54	constructor(radius float) {
...	...	@@ -55,15 +55,11 @@
55	55	this.radius = radius
56	56	}
57	57
	48	+ func Area() float {
	49	+ return PI * this.radius * this.radius
	50	+ }
	51	+
58	58	func Circumference() float {
59	59	return 2 * PI * this.radius
60	60	}
61	61	}
62		-
63		-1. Adding a function Area() to the GeometricObject interface is hard because it requires touching existing code, namely extending all Square and Circle classes with the new function.
64		-1. Adding a new datatype, Rectangle, is easy because only new code is added, namely a Rectangle class.
65		-
66		-### Conclusion
67		-
68		-* The lesson learned here is that data structures are easy to extend with functions, and objects are easy to extend with data types.
69		-* Although the difference between the two styles may seem insignificant in this simplified example, it has serious implications in complex production codebases with multiple data types and behaviors.