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构造时设置属性值

此示例说明如何定义 System object™ 构造函数并允许其接受名称-值属性对组作为输入。

将属性设置为使用名称-值对组输入

定义 System object 构造函数,该函数是一种与类(此示例中为 MyFile)同名的方法。在该方法内,使用 setProperties 方法来设置所有公共属性,使它们可在用户构造对象时用于输入。nargin 是一个 MATLAB® 函数,用于确定输入参数的数目。varargin 指示对象的所有公共属性。

methods 
   function obj = MyFile(varargin)
      setProperties(obj,nargin,varargin{:});
   end
end

包含构造函数设置的完整类定义文件

classdef MyFile < matlab.System
% MyFile write numbers to a file

    % These properties are nontunable. They cannot be changed
    % after the setup method has been called or while the
    % object is running.
    properties (Nontunable)
        Filename ="default.bin" % the name of the file to create
        Access = 'wb' % The file access character vector (write, binary)
    end

    % These properties are private. Customers can only access
    % these properties through methods on this object
    properties (Hidden,Access = private)
        pFileID; % The identifier of the file to open
    end

    methods 
        % You call setProperties in the constructor to let 
        % a user specify public properties of object as 
        % name-value pairs.
        function obj = MyFile(varargin)
          setProperties(obj,nargin,varargin{:});
        end
    end

    methods (Access = protected)
        % In setup allocate any resources, which in this case is
        % opening the file.
        function setupImpl(obj)
            obj.pFileID = fopen(obj.Filename,obj.Access);
            if obj.pFileID < 0
                error("Opening the file failed");
            end
        end

        % This System object writes the input to the file.
        function stepImpl(obj,data)
            fwrite(obj.pFileID,data);
        end

        % Use release to close the file to prevent the
        % file handle from being left open.
        function releaseImpl(obj)
            fclose(obj.pFileID);
        end
    end
end

另请参阅

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