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

Summary

• Page properties (2 modified, 0 added, 0 removed)

Details

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Parent

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1		-Main.WebHome
	1	+Software Engineering.Clean Code.Objects and Data Structures2.WebHome

Content

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7	7
8	8	### Data Structure Style
9	9
10		- struct Square {
	10	+ interface GeometricObject {}
	11	+
	12	+ class Square implements GeometricObject {
11	11	length float
12	12	}
13	13
14		- struct Circle {
	16	+ class Circle implements GeometricObject {
15	15	radius float
16	16	}
17	17
18		- function Circumference(g Object) float {
	20	+ function Circumference(g GeometricObject) float {
19	19	switch type(g):
20	20	case Square:
21	21	return 4 * g.length
...	...	@@ -23,8 +23,8 @@
23	23	return 2 * PI * g.radius
24	24	}
25	25
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.
	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.
28	28
29	29	####
30	30
...	...	@@ -57,3 +57,11 @@
57	57	return 2 * PI * this.radius
58	58	}
59	59	}
	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 here is that data structures are easy to extend with functions and hard to extend with data type, and objects are easy to extend with other objects but hard to extend with functionality.
	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.