CRC.Press A Guide to MATLAB Object Oriented Programming May.2007 Episode 2 Part 2 doc

194 A Guide to MATLAB Object-Oriented Programming

15.1.1.2 cLineStyle’s fieldnames

Whereas ctor_ini defines the collection of private variables, fieldnames defines the collec￾tion of public variables. In this case, there are only three: Color, LineWeight, and LineHan￾dle. The public variables and the values they hold come directly from the requirements. The code

to implement fieldnames for these public variables is shown in Code Listing 86.

4 this(1).mColorHsv = [2/3; 1; 1]; % [H S V]’ of border,

default is blue

5 this(1).mLineWidth = 1; % line weight: ‘normal’ == 1 ‘bold’

== 3

6 this(1).mLineHandle = []; % handle for shape’s line plot

7 superior = {};

8 inferior = {};

9 parents = {};

10 parent_list(parents{:});

Code Listing 86, Modular Code, cLineStyle’s fieldnames.m

1 function names = fieldnames(this, varargin)

2 names = {};

3

4 % first fill up names with parent public names

5 parent_name = parent_list; % get the parent name cellstr

6 for parent_name = parent_list'

7 names = [names; fieldnames([this.(parent_name{1})],

varargin{:})];

8 end

9

10 % returns the list of public member variable names

11 if nargin == 1

12 names = {'Color' 'LineWidth' 'LineHandle'}';

13 else

14 switch varargin{1}

15 case '-full'

16 names = {'Color % double array' ...

17 'LineWidth' % positive integer' ...

18 'LineHandle % plot handle'}';

19 case '-possible'

20 names = {'Color' {{'double array (3x1)'}} ...

21 'LineWidth' {{'positive integer'}} ...

22 'LineHandle' {{'plot handle'}}}';

23 Otherwise

24 error('Unsupported call to fieldnames');

25 end

26 end

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Constructing Simple Hierarchies with Composition 195

The parent-forwarding code in lines 4–8 is not necessary because parent_list returns an

empty cellstr. It is included because it is part of the standard template. When fieldnames

is called with one input argument, line 12 returns a cellstr populated with the three public

variable names. Lines 16–18 and 20–22 return additional information that depend respectively on

‘-full’ and ‘-possible’ flag values. In line 21, note the possible values for LineWeight

are ‘normal’ or ‘bold’.

15.1.1.3 cLineStyle’s get

The public variable section for cLineStyle’s get is shown in Code Listing 87. By now, the

code in this listing should look familiar. The value of found on line 2 is used to control entry

into subsequent concealed variable, parent-forwarding, and error code blocks. Inside the switch

beginning on line 3, there is a case for each public member variable. Lines 4–10 came directly

from the public member variable section of cShape’s previous implementation. The remaining

cases simply map one private variable into one public variable. This public variable section is just

about as easy as it gets. The remaining sections of cLineStyle’s get function use code from

the standard group-of-eight template.

Code Listing 87, Public Variable Implementation in cLineStyle’s get.m

1 % public-member-variable section

2 found = true; % otherwise-case will flip to false

3 switch index(1).subs

4 case 'Color'

5 if isempty(this)

6 varargout = {};

7 else

8 rgb = hsv2rgb([this.mColorHsv]')';

9 varargout = mat2cell(rgb, 3, ones(1, size(rgb,2)));

10 end

11 case 'LineWidth'

12 if isempty(this)

13 varargout = {};

14 else

15 varargout = {this.mLineWidth};

16 end

17 case 'LineHandle'

18 if isempty(this)

19 varargout = {};

20 else

21 varargout = {this.mLineHandle};

22 end

23 otherwise

24 found = false; % didn't find it in the public section

25 end

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