Design Patterns for Data Structures. Chapter 1. Abstraction

Transcription

1 Chapter 1 Abstraction

2 Figure 1.1 Type abstraction for type double double

3 Figure 1.2 Structure abstraction )$*+#$,!"#$%&'(",-,,,,./+0(",("&'$12,,,,./+0(",34.$ !"#$%&'("8("&'$1,9,:8;2

4 Figure 1.3 Statement abstraction load length, r1 load width, r2 add r1, r2, r3 mul 2.0, r3, r3 store r3, perim perim = 2.0 * (length + width);

5 Figure 1.4 Procedure abstraction double perimeter(rectangle r) { return 2.0 * (r.length + r.width); } cout << perimeter(myrectangle); 9;<0&>>&!"#$%"0"#,%78"90:./-"56!"#$%&&%'()*+($(),-"#).(!$/012(34

6 *0$%1!5,*0$%+6%*0$%03%7 %%%%*8%,9%::%03%7 %%%%%%%%)($#)0%+4 %%%%;%(2<(%7 %%%%%%%%)($#)0%1!5,06%+%=%034 %%%%; ; $(+'%:%1!5,0#+6%5(0"+34

7 Figure 1.5 Class abstraction struct Rectangle { double length; double width; }; double area(rectangle r); double perimeter(rectangle r); class Rectangle { private double length; double width; public double area(); double perimeter(); }; Rectangle length: double width: double + area( ): double + perimeter( ): double

8 OO terminology class type object variable method procedure function

9 Figure 1.6

10 #(%)),!"#$%&'(",- 6*47%$"8,,,,./+0(",("&'$12,,,,./+0(",34.$12 6+0(4#8,,,,./+0(",%*"%9:2,,,,./+0(",6"*4;"$"*9:2 52!"#$%&'(&)*+,-%&../&012&*&034'5 ''''0&*#0,'678'9'3%&,-*:';'<1!*:4= >!"#$%&'(",;<!"#$%&'("2

11 Figure 1.7 Behavior abstraction ehavior abstraction for shapes rendered geometrically.

12 Figure 1.7 Abstract Shape avior abstraction for shapes rendered with the UML symbol for inheritanc

13 Figure 1.8 The abstract shape class AShape + area( ): double + perimeter( ): double + scale(factor: double) + display( ) + promptandsetdimensions( )

14 Figure 1.8

15 Figure 1.9 The rectangle subclass class Rectangle : public AShape { private: double _length; double _width; public: Rectangle(double length = 0.0, double width = 0.0); // Pre: length >= 0.0 and width >= 0.0. // Post: This rectangle is initialized with // length length and width width. }; double area() override; double perimeter() override; void scale(double factor) override; void display(ostream &os) override; void promptandsetdimensions() override;

16 Figure 1.10 AShape + area( ): double + perimeter( ): double + scale(factor: double) + display( ) + promptandsetdimensions( ) _length: double _width: double Rectangle + Rectangle(length: double, width: double) + area( ): double + perimeter( ): double + scale(factor: double) + display( ) + promptandsetdimensions( )

17 Figure 1.11

18 Figure 1.11 void Rectangle::scale(double factor) { cerr << scale: Exercise for the student. << endl; throw -1; } void Rectangle::display(ostream &os) { os << Rectangle << endl; os << Length: << _length << endl; os << Width: << _width << endl; } void Rectangle::promptAndSetDimensions() { _length = promptdoublege( Length?, 0.0); _width = promptdoublege( Width?, 0.0); }

19 Figure 1.12 Component diagram AShape.hpp Rectangle.hpp Rectangle.cpp

20 Figure 1.13 The C++ try/catch/throw statement

21 Figure 1.14 Class diagram for abstract and concrete shapes AShape + area( ): double + perimeter( ): double + scale(factor: double) + display( ) + promptandsetdimensions( ) Line _length: double + Line(length: double) Circle _radius: double + Circle(radius: double) NullShape Rectangle _length: double _width: double RightTriangle _base: double _height: double + Rectangle(length: double, width: double) + RightTriangle(base: double, height: double)

22 Demo dp4ds Shape project

23 Figure 1.17 Specification of shape main program

24 Figure 1.17

25 Figure 1.18 Visual depiction of parameters shapes[0] shapes[1] shapes[2] shapes[3] sh (a)visual depiction of parameter sh. shapes[4] (b)visual depiction of parameter shapes.

26 Figure 1.19 The ShapeMain program

27 Figure 1.19

28 When the new operator executes, it

29 Figure 1.20

30 Figure 1.20

31 Figure 1.21

32 Figure 1.21

33 When the new operator executes on an object, it

34 Figure 1.22

35 Figure 1.23 The abstraction process Data Control Type abstraction Statement abstraction Structure abstraction Procedure abstraction Rectangles Class abstraction Behavior abstraction Data Control Type abstraction Statement abstraction Structure abstraction Procedure abstraction Circles Class abstraction