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

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...	...	@@ -1,25 +1,69 @@
1		-asd
	1	+### Use Cases
2	2
3		-```
4		-type Square struct {
5		- length float
6		-}
	3	+This example is intended to demonstrate the extensibility differences between data structures and objects by extending them with
7	7
8		-type Circle struct {
9		- length float
10		-}
	5	+1. an Area() function (extending behavior)
	6	+1. a rectangle type (extending data type)
11	11
12		-func Area(g GeometricObject) float {
13		- switch (g.type()):
14		- case Circle:
15		- return
16		- case Square:
17		- return ...
18		-}
	8	+### Data Structure Style
19	19
20		-func Circumference(g GeometricObject) float {
21		- ...
22		-}
23		-```
	10	+ interface GeometricObject {}
	11	+
	12	+ class Square implements GeometricObject {
	13	+ length float
	14	+ }
	15	+
	16	+ class Circle implements GeometricObject {
	17	+ radius float
	18	+ }
	19	+
	20	+ function Circumference(g GeometricObject) float {
	21	+ switch type(g):
	22	+ case Square:
	23	+ return 4 * g.length
	24	+ case Circle:
	25	+ return 2 * PI * g.radius
	26	+ }
24	24
25		-asd
	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	+#### Object-Oriented Style
	34	+
	35	+ interface GeometricObject {
	36	+ Circumference() float
	37	+ }
	38	+
	39	+ class Square implements GeometricObject {
	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	+
	51	+ class Circle implements GeometricObject {
	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	+ }
	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.